Which of the following is most likely a correct statement about the strengths and weaknesses of the CAPM model? I. Richard Roll, in his 1977 paper. criticized CAPM stating that it lacks theoretical grounds. II. It is a weakness that CAPM applies to expected returns, instead of actual returns. III. It is a strength that it is difficult to find a truly diversified portfolio, which is one of the key inputs of the CAPM. IV. The APT model is an enhanced version of the CAPM model theoretically, but not so empirically. III I and II O