Spot the doubled-referent error and choose the standard sentence about a flat.
The flat that I rented near campus was quiet.✓Respuesta correcta
The flat that I rented it was quiet.
The flat which I rented it was quiet.
The flat I rented it was quiet.
Explicación
That already represents the flat as the object of rented, so no object pronoun is needed inside the clause. The version with it is the closest distractor because it assigns the same object role twice.