1. Which of the following statements best describes the contribution margin? a. The contribution margin is defined as fixed costs minus variable costs b. The contribution margin is the dollar amount of per unit revenue that contributes to profit. c.The contribution margin is defined as revenues minus fixed costs. d. The total contribution margin is defined as the contribution margin multiplied by total revenues. e. The contribution margin is the amount of per unit revenue that is available to first cover fixed costs and then to contribute to profitability