What type of source is this, and how do you know that?

Its B because it was clearly written at the time that it was happening.

the right answer is the third one: turnpikes went short distances to connect markets. turnpikes, also known as toll roads, were very important for trade and transportation (of people, goods and products) in the 19th century, coinciding with the expansion towards the west. they contributed significantly to the economic development of the united states.