Which of the Following Is True

Which of the following is true?

A) Once stock is issued, it is illegal for a company to buy back its own stock.
B) Most common stock holders exercise their voting rights in a corporation even if they own a very few shares of the stock.
C) Initial Public Offerings (IPOs) of new stock are done only on organized exchanges.
D) Previously issued shares of stock are traded either on organized exchanges or over-the-counter.