Which of the following statements below is/are correct? There might be more than one correct answer. Choose your selection carefully. Select one or more: a. The beta of a stock is fixed and does not change over time b. Alpha is the slope of the characteristic line c. The market portfolio contains all securities within the market and the weight of each security is its market value as a percentage of the total market d. The Capital Asset Pricing model states that a linear relationship holds between systematic risk and expected return