She was wondering whether they've (A) completed their lifeguard training.
Answer: It’s help other actors recognize their cue.
It’s D :)
When reading a play it is easier to imagine what's happening on stage if the stage directions there. We can picture how the actors are looking and what they're doing. And if you are acting in the play itself then it gives you information for what your character does next whether its 'exit stage left' or 'enter stage right' for example.
