What is the purpose of a line agency?
a. support the agency
c. actually do the tasks of the agency
b. rewrite the goals of the agency
d. name the agency

Line agencies, either in public administration or the military or different businesses, are those departments within an organization which focus on the primary function and work of the organization. The key line agencies in businesses are  production, sales and marketing.
Thus, the answer is letter C.  actually do the tasks of the agency