Mr. Busy has just enough time in which to complete any one of the following tasks; vacuum his apartment, write a letter to his mother, and buy groceries. The dollar values that Mr. Busy places on these individual tasks are, respectively; $26, $31, and $29. What is Mr. Busy's rational choice and what is its opportunity cost? (a) Buy groceries, $57. (b) Write to his mother, $55. (c) Vacuum his apartment, $60. (d) Buy groceries, $26. (e) None of the above."