Definition: You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
Input: Question: A bullet train covers a distance in 50 min, if it runs at a speed of 48kmph on an average. The speed at which the bullet train must run to reduce the time of journey to 40min will be.

Option A: 80 kmph

Option B: 40 kmph

Option C: 60 kmph

Option D: 90 kmph

Option E: 30 kmph
Output:
Option C