Commercial agriculture consists of raising food for trade and profit, while subsistence agriculture focuses on - -

a. providing the basic needs of the farmer's family

b. providing the basic needs of the neighboring communities

c. creating more arable land for future use

d. obtaining subsidies from governments and corporations

A. Providing the basic needs of the farmer's family.

One of the definitions of "subsist" is to "support or maintain." The farmer's family subsists off of their harvest, so they are almost entirely capable of supporting themselves with the crops that they grow, or the livestock that they raise. Hence, A is the correct answer.