A company has the following capital stock outstanding: preferred shares of $15,000, common shares of $30,000, retained earnings of $100,000. Preferred dividends in arrears amount to $5,000. There are 10,000 shares of common stock and 1,000 shares of preferred outstanding. What is the book value of one share of common stock?

a. $12.50

b. $20

c. $105

d. $125