Task: Question Answering
Input (English): Question: A person can walk at a constant rate of 8mph and can bike at a rate of 16mph. If he wants to travel 72 miles in 8 hours using bike and walking at their constant rates, how much distance would he require to walk?

 Option A: 20

 Option B: 30

 Option C: 48

 Option D: 56

 Option E: 72
Output (English): Option D