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: If 10 typists can type 20 letters in 20 minutes, then how many letters will 40 typists working at the same rate complete in 1 hour?

 Option A: 220

 Option B: 210

 Option C: 200

 Option D: 240

 Option E: 260

Option D