Tricky one!
A play definitely must have an actor in its cast. How would you have a play without actors? People would just stare at the scenery?
I think the easiest way to get this question right is just process of elimination.
There's no way to infer (A) since the information only talks about whether a cast includes males or females. It says nothings about how MANY males or females are in the plays.
The five plays with females in them might only have 1 female each, while the four plays with males in them might have 100 males each. Who knows?
And, naturally, it would be too easy , too much of a trap answer to say that there are more female actors, because it matches up too easily with the "5 female, 4 male" info provided.
A real inference should require a little mental work, as (B) definitely does.
If you have six plays, and only five of them have females in them, then what do you know about the sixth play?
It must have only males.
So let's just call that play 6 and know it has only males.
What's left?
5 plays, all of which have females in them. And 3 of them have to have males in them.
So 3 of the 5 plays have males and females. And so that means that 3 of the 6 plays have males and females (since we know that play 6 is just males).
(by the way, since this typing environment removes all extra spaces, it was hard for me to judge how you intended for your two scenarios to look. It seemed like some of the extra spacing you did was deleted, so I can't really comment on whether your two scenarios were accurate)
Let me know if you have lingering questions about this one.