How did the 1918 flu end?

By the summer of 1919, the flu pandemic came to an end, as those that were infected either die d or developed immunity. Almost 90 years later, in 2008, researchers announced they’d discovered what made the 1918 flu so dea d ly: A group of three genes enabled the virus to weaken a victim’s bronchial tubes and lungs and clear the way for bacterial pneumonia. Since 1918, there have been several other influenza pandemics, although none as de adly. A flu pandemic from 1957 to 1958 k illed around 2 million people worldwide, including some 70,000 people  in the United States, and a pandemic from 1968 to 1969 kill ed approximately 1 million people, including some 34,000 Americans. More than 12,000 Americans perished during the H1N1 (or “swine flu”) pandemic that occurred from 2009 to 2010.

it would be  

germany had to pay all damages related to the war.

and i think

germany had to take sole responsibility for the war.

i would say b. or c.