The Correct answer is E.

Explanation

Among the??seniors, there are??boys for every??girls, so??of the seniors, or?, are boys and?, or?, are girls. Among the juniors,??are boys and??are girls. If??stands for the total number of juniors, then??are boys and??are girls. The total number of senior and junior boys is?. The total number of senior and junior girls is?. The question states that these quantities are equal, so?. Solving this gives?, or?.