A professor with a Ph.D in economics can write a short essay in economics in 3 hours and can mow the lawn in 6 hours. A student in economics can write a short essay in economics in 6 hours and can mow the lawn in 6.5 hours. Which of the following is true? A: the professor should write the essay since he has the comparative advantage in writing. B: the professor should do both the jobs as he can finish both jobs in a shorter time period. C: the student should write the essay since he had the comparative advantage in writing D: the professor should write the essay since he has the absolute advantage in writing