Which of the Following Statements Are Correct

Which of the following statements are correct?
I.The SML approach is dependent upon a reliable measure of a firm's unsystematic risk.
II.The SML approach can be applied to firms that retain all of their earnings.
III.The SML approach assumes a firm's future risks are similar to its past risks.
IV.The SML approach assumes the reward-to-risk ratio is constant.

A) I and III only
B) II and IV only
C) III and IV only
D) I, II, and III only
E) II, III, and IV only