The accompanying table shows the marginal private benefit, marginal social benefit, and marginal private cost for you to exercise to improve your health.

a. Why does the marginal private cost of exercise rise as hours of exercise per week rises? 

b. Why does the marginal private benefit fall as hours of exercise per week rises? 

c. Why do the private marginal benefits of exercise differ from the social marginal benefits of exercise? 

d. What happens to the size of the positive externality associated with exercise as hours of exercise per week rises? Why? 

e. If this market were purely private, what would be the optimal number of hours of exercise per week for you? 

f. What is the socially optimal number of hours of exercise per week for you? 

g. What are some methods that society uses to get from the private optimum level of exercise to the socially optimum level of exercise?