Task: Question Answering
Input (English): Question: Three taps A, B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, the tank will be full in:

 Option A: 6 hours

 Option B: 20/3hours

 Option C: 7 hours

 Option D: 15/2hours

 Option E: 17/2hours
Output (English): Option C