Task: Question Answering
Input (English): Problem: a swimmer can swim in still water at 4 km / h. if the speed of the water current is 2 km / h, how many hours will the swimmer take to swim against the current for 5 km ?
Options: a. 2.0, b. 2.5, c. 3.0, d. 3.5, e. 4.0
Output (English): b