Answer:
The sentence that is written in active voice is D. "We will provide your password after you have completed the form."
Active Voice Structure
Active voice follows the structure of Subject + Verb + Object
The emphasis is on the person that carries out the action.
WE (subject)+WILL (auxiliar)+ PROVIDE (verb)+YOUR PASSWORD (object)
Passive Voice Structure
Passive voice follows the structure of OBJECT + BE + PAST PARTICIPLE/-ED
The emphasis is not on the person but on the object.
YOUR PASSWORD (object)+ WILL (auxiliar) +BE(verb "BE") + GIVEN (past participle)