Concept: The question tests on the area of Modern Math/Counting

Solution:

We have 7 boys of team 1 and 5 girls of team 2. The number of matches that can be played is

 7C1 * 5C1 = 7 * 5 = 35

 Similarly, We have 5 boys of team 2 and 3 girls of team 1.

 The number of matches that can be played is

5C1 * 3C1 = 15

The total number of matches is 35 + 15 = 50

Option