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: What is the least number to be subtracted from 11, 15, 21 and 30 each so that resultant numbers become proportional?

 Option A: 5

 Option B: 6

 Option C: 3

 Option D: 8

 Option E: 1

Option C