C - The Greeks built the horse to win back the favor of Athena
Explanation:
Sinon tells the trojans the horse is meant to win back the favor of Athena from previous desecration of her temple and to guarantee a safe journey home for the Greek fleet.
He also persuaded them to take the horse by pretending to have escaped from the Greeks when they tried to sacrifice him. He then went on to tell them that the gods had told them to create a sacred image which could replace the Palladium for protecting Troy.
The Greeks, pretending to desert the war, sailed to the nearby island of Tenedos, leaving behind Sinon, who persuaded the Trojans that the horse was an offering to Athena (goddess of war) that would make Troy impregnable.
