Task: Question Answering
Input (English): Question: One pipe can fill a pool three times faster than a second pipe. When both pipes are opened, they fill the pool in seven hours. How long would it take to fill the pool if only the slower pipe is used?

 Option A: 10 hr

 Option B: 12 hr

 Option C: 15 hr

 Option D: 20 hr

 Option E: 28 hr
Output (English): Option E