Since the play must be performed by equal numbers of male and female actors and there are only 2 male actors to choose from, the play must be performed by either 1 male and 1 female actor or 2 actors of each gender.

If the play is performed by 1 male and 1 female actor, there are 2 possible choices for the male actor and 5 choices for the female actor. The total number of 1 male/1 female performing groups is (2)(5) = 10.

If the play is performed by 2 male and 2 female actors, there is only one choice for the male actors -- we simply choose both of them. To choose 2 different female actors, we need to use the combinations formula, where the overall set is 5, and the desired subset is 2:
5! / (5 - 2)!(2)!
= 5! / 3!2!
= (5)(4) / 2
= 10
Thus, there are 10 groups with 1 male and 1 female actor, and 10 groups with 2 male and 2 female actors. That's a total of 20 combinations, choice (B).