Teacher:Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.
Teacher: Now, understand the problem? Solve this instance: 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
Student:
b