Task: Question Answering
Input (English): Question: Two pipes can fill the cistern in 10hr and 12 hr respectively, while the third empty it in 15hr. If all pipes are opened simultaneously, then the cistern will be filled in

 Option A: 7.5 hr

 Option B: 8 hr

 Option C: 8.57 hr

 Option D: 10 hr

 Option E: None of these
Output (English): Option C