Given the task definition and input, reply with output. 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.

Question: In a local school district, the high school and middle school each received r dollars toward funding for the student arts program. The high school enrolled 600 students and the middle school enrolled 300 students. Later, the middle school transferred s dollars to the high school so that they would have received the same funding per student. Which of the following is equivalent to s?

Option A: r/3

Option B: r/2

Option C: 2r

Option D: 3r

Option E: r/9
Option A