Stock A's beta is 1.5 and Stock B's beta is 0.5. Which of the following statements must be true about these securities? (Assume market equlibrium.) a. Stock A must be a more desirable addition to a portfolio than Stock B. b. The expected return on Stock A should be greater than that on Stock B. c. The expected return on Stock B should be greater than that on Stock A. d. When held in isolation, Stock A has greater risk than Stock B. e. Stock B must be a more desirable addition to a portfolio than Stock A