16. Suppose that a pair of events from problem 15 occur simultaneously. For each of the pairs of events indicated below, perform a qualitative analysis to predict the direction of change in either the equilibrium price or the equilibrium quantity. Explain why the change in one of these two variables is indeterminate.

a. Both a and h in problem 15 occur simultaneously.

b. Both d and e in problem 15 occur simultaneously.

c. Both d and h in problem 15 occur simultaneously.

d. Both f and c in problem 15 occur simultaneously.