The market value of common stock is primarily based on:

A) the firm's future earnings.
B) book value.
C) total assets.
D) retained earnings.

The value of a company's common stock is primarily based on investors' expectations of the company's future earnings, as reflected in its current and projected financial performance, growth prospects, and other relevant factors. Book value, total assets, and retained earnings are important factors in evaluating a company's financial health and stability, but they do not necessarily indicate its future growth potential or market value.