Task: Question Answering
Input (English): Question: There are 20 balls which are red, blue or green. If 7 balls are green and the sum of red balls and green balls is less than 13, at most how many red balls are there?

 Option A: 4

 Option B: 5

 Option C: 6

 Option D: 7

 Option E: 8
Output (English): Option B