C. explanations about how the actors sound and behave This is the correct version.
Stage directions are made up of explanations. These give the play readers information about the attitude of the characters and this information makes the play more comprehensible.
These options are not right:
a. central message about life. ( Stage directions are present in a play. They are focused on actors' performance , not on philosophical reflections. A character from the play can give this message about life).
B. the meaning behind events and characters’ actions. ( Stage directions do not analyse what happens in the play).
D. writing that is vague and uncertain. ( On the contrary, the stage directions have to be clear and certain to guarantee the comprehension of the play).
