Task: Question Answering
Input (English): Problem: the ratio between the present ages of a and b is 3.5: 3 respectively. the ratio between a ' s age 4 years ago and b ' s age 4 years hence is 1: 1. what is the ratio between a ' s age 4 years hence and b ' s age 4 years ago ?
Options: a. 14: 4, b. 13: 0, c. 15: 11, d. 13: 12, e. 13: 17
Output (English): c