Final answer:
Ares is the correct answer to the question as he is the son of Zeus and Hera and known as the god of war according to Greek mythology.
Step-by-step explanation:
The Greek god who was a son of Zeus and Hera is Ares, making option a. Ares the correct answer. Ares is known as the god of war in Greek mythology, and he is one of the twelve Olympian gods and goddesses who resided on Mt. Olympus. His character is associated with the brutal and bloody aspect of warfare, making him less favorable among the pantheon and followers.
Despite this, Ares counts amongst the major deities of Greek religion due to his parentage and significant role in mythological tales. The other choices given, namely Apollo, Athena, and Amphion, are incorrect based on the established myths; Apollo and Athena are indeed children of Zeus, but their mothers are not Hera, and Amphion is not a son of Zeus and Hera .