Read the passage. The Great San Francisco Fire

The San Francisco earthquake of 1906 was one of America’s largest natural disasters. The shaking lasted only 45 to 60 seconds, but it caused many of the brick and wooden buildings to collapse, trapping many victims. But the worst was yet to come. The tremors from the earthquake had ruptured gas lines. The quake also destroyed the entire fire alarm system in the city. At the time, glass wet batteries were used for the alarms. These were glass jars full of electrolytic solution with copper electrodes. Of the 600 glass wet batteries that operated the system, 556 of them had broken. Within a few hours of the quake, 52 fires broke out, but no alarm was ever sounded for the fires.

The first fire to break out after the quake was at a Chinese laundry across the street from a firehouse. However, there was no water to fight it since the water mains had been ruptured by the quake. The main reservoirs of water for the city were 20 miles away, and some of the pipelines to them had been destroyed because they were constructed along the quake’s fault line. The blaze soon roared like a seething, famished beast lapping up its spoils. Then two massive fires flared up within two blocks of each other in the Western Addition section of the city. Another one broke out in the Mission District. In the downtown area dozens of fires erupted. Firefighters were able to quell the flames in the Western Addition with the use of three fire engines. The fire in the Mission District was subdued with water found blocks away in a hydrant. Then the firefighters began to head downtown to try and extinguish the fiery deluge there. Most of the large fires downtown became one. At one point it became a three-mile-wide wall of raging flames with billowing black clouds of smoke. In one area, a cistern that held 100,000 gallons of water was drained completely without making a dent in the spewing blaze. Fireboats sprayed water in a desperate attempt to quash the fuming flames along the waterfront.

All telephone and telegraph communications in the city were cut off. An hour after the quake struck, a messenger from the San Francisco Fire Department was dispatched to Fort Mason to ask for troops to help combat the fires. The troops also helped to prevent people from looting items that did not belong to them to replace those they had lost in the fires or to take things they couldn’t afford to buy. An aftershock at 8:14 a. m. caused many of the damaged buildings to collapse into a contorted, sickening pile of ruin.

More than 50 fires scorched the city like an inferno in the three days following the earthquake. Wind whipped flames into a lurid frenzy. Several blazes started during the shaking. Many more were accidently from people cooking inside damaged homes or building campfires after the quake. One woman started a fire in her stove to make breakfast, but the chimney in her house had been damaged from the earthquake. The small flame flared since there was no way to vent it, and the house became engulfed. This fire was called the “ham and egg fire” and was believed to have burned more property than any other single fire. It was responsible for the destruction of City Hall. As fires spread, some of them joined together and became rolling, fiery maelstroms.

On the evening of the second day of the raging fires, the army began using dynamite to destroy buildings that were already on fire so there would be less fuel to feed them. They hoped that would stop the flames from spreading further. Unfortunately, some of the explosions caused more fires. With few other options to save the rest of the city, more explosives were used to create two important fire breaks. The army blew up stately mansions along Van Ness Avenue and many buildings in the Mission District to starve the fires. On the third day the fires stopped in the middle of a block of wooden-framed homes. Two days later, the army dynamited structures that were on the verge of collapse. Some of them were seven stories tall. The Call Building, a city landmark recognizable by its dome, burned. A fireball blasted up through its elevator shafts and blew out the dome. Although the interior was destroyed, the structure itself remained. The building was refurbished and today is called Central Tower.

The fires destroyed a total of 28,188 buildings and burned 4.7 square miles of San Francisco. The estimated monetary loss was more than $400 million. But the human casualties were horrific. It is estimated that more than 3,000 deaths were caused by the earthquake and resulting fires. The population of San Francisco at the time was approximately 400,000 people. Of those, 225,000 people were left homeless.

Which feature, when included with this passage, would best aid a reader's comprehension?

a series of photographs of San Francisco during the fires

subheadings above each paragraph

a photograph of modern-day San Francisco

a map showing where the fires burned in 1906