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: at their respective rates, pump a, b, and c can fulfill an empty tank, or pump - out the full tank in 2, 3, and 6 hours. if a and b are used to pump - out water from the half - full tank, while c is used to fill water into the tank, in how many hours, the tank will be empty ?
Options: a. 2 / 3, b. 1, c. 3 / 4, d. 3 / 2, e. 2
Student:
c