Q: 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.
Problem: a train 700 m long is running at a speed of 78 km / hr. if it crosses a tunnel in 1 min, then the length of the tunnel is ?
Options: a. 288 m, b. 256 m, c. 600 m, d. 278 m, e. 287 m
A:
c