Answer:
e. increase as the probability of a boom economy increases.
Explanation:
The most economic growth occurs when the economy is in boom state. This results in the highest rate of return on investments compared to all other states such as normal, recession. In this case, if the probability of boom economy increases, stock S will have an overall increase in expected return; it means that there is higher chance of earning 12% return which is the highest among those in other economy states. This makes choice E correct.