Task: Question Answering
Input (English): Question: Working together, John, David, and Roger require 2 1/4 hours to complete a certain task, if each of them works at his respective constant rate. If John alone can complete the task in 4 1/2 hours and David alone can complete the task in 9 hours, how many hours would it take Roger to complete the task, working alone?

 Option A: 2 1/3

 Option B: 4 1/2

 Option C: 6 3/4

 Option D: 9

 Option E: 12
Output (English): Option D