Which of the Following Is True About a "Buy-And-Sell" Agreement

Which of the following is true about a "buy-and-sell" agreement among corporate shareholders?

A) They are most often entered into among shareholders of large, publicly-held corporations, since it is otherwise difficult to monitor the large number of stock transactions.
B) They always provide for the purchase of shares by the corporation, in the event a shareholder desires to sell shares.
C) They can provide for the sale of shares to either the corporation or to other shareholders at the price specified in the agreement.
D) They usually also contain an agreement for a voting trust.
E) They are enforceable, but only if the agreement provides for a fair price.