Answer:
A) Whom are you taking to the play?
Step-by-step explanation:
The correct used is in option A, its grammar is well used and good written. Other option have mistakes.
Option B: ''Your'' is the mistake, the right way is ''You're''.
Option C: ''Its'' is wrong, it should be ''It's''.
Option D: ''Their'' is wrong, the right way is ''They're''.
These type of mistakes are really common and confusing for many students.