Answer: El señor Smith es el director de la escuela Saint Andrews.
Explanation: The sentence that we must complete is:
"El señor Smith es ________ de la escuela Saint Andrews."
This means:
"Mr. Smith is the ____ of the Saint Andrews school"
The options are:
La directora (The principal, used in feminine cases)
El maestro (The teacher, used in masculine cases)
La maestra (The teacher, used in feminine cases)
El director (The principal, used in masculine cases)
Because of the sentence, we know that the correct answer is one of the two masculine cases, and now, you usually won't say "The teacher", you would say "A teacher" (because there are many teachers in a school) so the right answer is "El director"
El señor Smith es el director de la escuela Saint Andrews.