anyone good at economics please assist?

[GRL]

1.) suppose that an MBA degree creates no externality because of the benefits of an MBA are internalized by the student in the form of higher wages. If the government subsidies for MBAs, then which of the following statements is correct?
a. the equilibrium quantity of MBAs will equal the socially optimal quantity of MBAs
b. the equilibrium quantity of MBAs will be greater than the socially optimal quantity of MBAs
c. the equilibrium quantity of MBAs will be less than the socially optimal quantity of MBAs

2.) most economists prefer corrective taxes to regulation to correct the pollution problem because
a.) the market-based solution is less costly to society
b.) the market based solution can result in a greater reduction in population
c. the market based solution raises revenue for the government
d.) all of the above

the answer for 1 is B and the answer to 2 is D can someone please explain why to me?