Task: Question Answering
Input (English): Question: A and B together can do a piece of work in 6 days and A alone can do it in 9 days. In how many days can B alone can do it?

 Option A: 12 days

 Option B: 15 days

 Option C: 18 days

 Option D: 21 days

 Option E: 22 days
Output (English): Option C