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 car traveling at a certain constant speed takes 4 seconds longer to travel 1 km than it would take to travel 1 km at 80 km / hour. at what speed, in km / hr, is the car traveling ?
Options: a. 70, b. 72, c. 74, d. 75, e. 78
Student:
c