Task: Question Answering
Input (English): Question: In a certain city each of 17 Girl Scout troops is represented by a colored flag. Each flag consists of either a single color or a pair of two different colors. If each troop has a different flag, what is the minimum number of colors needed for the flags. (Assume that the order of colors in a pair on a flag does not matter.)

 Option A: 5

 Option B: 10

 Option C: 6

 Option D: 20

 Option E: 40
Output (English): Option C