Which of the following statements are true? 1. Because there is a limited supply of shares of any stock to be borrowed by would-be short sellers, unlimited short selling is a problematic assumption for CAPM. II. Transaction costs continue to become smaller, so this factor is no longer considered a problem for CAPM III. CAPM assumes that markets are efficient. IV. One of the most important attributes of CAPM was its contribution to understanding the relationship between risk and return. Only II and I are true. Only I. III, and IV are true Only II,III, and IV. All of the statements are true. Only IV and I are true