Wage decreases lead to a decrease in aggregate quantity supplied

Consider the hypothetical supply and demand of Kidneys.

Initially, kidneys are exchanged by donations only (price=0). If the government decides to legalize kidney sales and the market reaches equilibrium, then:

A. total surplus increases.
B. consumer surplus remains the same.
C. producer surplus remains the same.
D. a shortage of kidneys will arise.

When do new firms tend to enter a competitive industry?

a. When the large firms in the industry are earning zero profit. b. When the smaller firms are leaving the industry. c. When the new entrants can earn positive profits. d. When there is an absence of fixed costs in the long run.