The economic way of thinking pays special attention to costs, assumes individuals seek to maximize some objective, and focuses on choices at the margin.

A horizontal supply curve of labor implies that

a. lower wages are required to attract more employees b. higher wages are required to attract more employees c. MPP is constant d. any quantity of workers can be hired at the same wage e. the total labor cost curve is horizontal

Refer to the accompanying table below. According to the Cost-Benefit Principle, how many units of this activity should be carried out?Units of ActivityTotal CostTotal Benefit0$0$01$30$1002$40$1603$60$1904$100$2105$150$2206$210$225 

A. 6 B. 1 C. 4 D. 3