Task: Question Answering
Input (English): Question: Two pipes A and B can separately fill a tank in 20 and 15 minutes respectively. A third pipe C can drain off 45 liters of water per minute. If all the pipes are opened, the tank can be filled in 15 minutes. What is the capacity of the tank?

 Option A: 590 liters

 Option B: 540 liters

 Option C: 820 liters

 Option D: 900 liters

 Option E: 580 liters
Output (English): Option D