You sent your job application to someone.
b. to is a preposition
for a preposition phrase that's an adverbial for direction/place
c. Steps: insert,
move the whole prepositional phrase as a unit, add did to have an
operator, change sent to send because only the first word
in the verb phrase can have tense
You sent your job
application to whom?
To whom you sent
your job application?
To whom did you
send your job application?
If you move the preposition
to the front with the wh- word, you must use whom.
If you leave the preposition
at the end and just move the wh- word, you can use who.
Who did you send
you job application to?