At the end of the 18th century, approximately percent of the american people earned a major portion of their income by farming.

Right answer is (this is sure):

At the end of the 18th century, approximately 90% percent of the American people earned a major portion of their income by farming.

Explanation:

The US population was nearly 4 million in 1790. 90% of them made a living in agriculture.  That means that post-revolutionary America was an eminently agrarian country.  

a.) a poor farmer, due to the fact that they would want to be freed from british rule.