Task: Question Answering
Input (English): Problem: pipe a fills a swimming pool in 4 hours. pipe b empties the pool in 6 hours. if pipe a was opened at 6: 00 am and pipe b at 7: 00 am, at what time will the pool be full ?
Options: a. 14: 00, b. 15: 00, c. 13: 00, d. 16: 00, e. 17: 00
Output (English): d