Treasury Stock or Treasury Shares Are Shares a Firm Has

Treasury stock or treasury shares are shares a firm has previously issued and later reacquired. Which of the following is/are true?

A) Some firms believe that their own shares provide a good investment.
B) Evidence supports the notion that share prices often increase after a firm announces a share repurchase program.
C) Share repurchases reduce common shareholders' equity and increase the proportion of debt in the capital structure, making the firm more risky and therefore less attractive to an unfriendly bidder.
D) Some firms even borrow cash to repurchase shares, which affects the debt ratios even more than using already available cash to reacquire shares.
E) all of the above