Which of the Following Statements Is Most Correct

Which of the following statements is most correct?

A) If a company has two classes of common stock, Class A and Class B, the stocks may pay different dividends, but the two classes must have the same voting rights.
B) An IPO occurs whenever a company buys back its stock on the open market.
C) The preemptive right is a provision in the corporate charter which gives common stockholders the right to purchase (on a pro rata basis) new issues of common stock.
D) Statements a and b are correct.
E) Statements a and c are correct.