The largest single share of all income earned by Americans consists of:

The knowledge and skills acquired by a worker through education and experience is a description of which factor of production?

A) physical capital B) entrepreneurship C) labor D) human capital

In order to be classified as a recession, a contraction of general economic activity must last at least

A) one year. B) six months. C) one period. D) one quarter. E) None of the above because recessions do not have a minimum length.