You will be given a definition of a task first, then some input of the task.
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: Which is a better investment 9% stock at 580 or 6 2/5 stock at 312?

Option A: 9% stock at 580

Option B: Both are equally good

Option C: 6 2/5 stock at 312

Option D: None

Option E: Cannot be compared, as the total amount of investment is not given
Output:
Option C