Question

Rocio ya había __________________ la película.

Answer 1

The answer is visto or mirado which is the same thing but is used in different ways

Answer 2

Mirado doesn't really fit in this case, because it's like saying Rocio already "looked" the movie. Mirado is the past participle of look.
Visto however is the answer because visto means "saw", and without a discussion the word "saw" makes more sense than "looked"