Marvin and Zelda are both 51 and intend to retire when they are 62. Both have a traditional and Roth IRA. They also have a regular investment account which has emphasized growth and has built up to a substantial amount. Which of the following actions would give them additional income after retirement and best minimize their taxes? Question 17Select one: a. Purchase a high-income mutual fund that holds U.S. debt obligations and state bonds b. Purchase a high-income mutual fund that holds corporate bonds and U.S. debt obligations c. Purchase treasury bills and treasury bonds directly d. Maximize contributions to their Roth IRAs every year