In the play crossroads: a sad vaudeville, the use of stage directions better the reader
a. observe the movements of a character
b. envision inside the mind of a character
c. understand how a character responds to a certain situation
d. all of the above
i think it's a or d, but i'm not sure which one.

The best option here is answer D. Specifically the playwright's directions could be argued as simply providing A. ie detail on the movement on stage of the characters for the use of the director and actors. However this will of course without doubt provide detail that goes deeper and so covers the areas outlined as options B and C as well.

B. metaphor is the answer