Answer:
a. select the board of directors of a corporation.
Step-by-step explanation:
The board of directors is elected by the stockholders of a company and they are the ones responsible for hiring CEO, CFO, and the rest of the upper management of a corporation. They are also in charge of setting the corporate strategy and making important decisions, e.g. approving new projects, etc.
Stockholders do not control the company directly, the board does.