What is the Greek counterpart to the Roman god Mars?

The correct answer is B, Ares, because Ares is the Greek god of war, and he corresponds directly to Mars, the Roman god of war. Both Ares and Mars embody similar attributes and roles within their respective mythologies, representing the violent and tumultuous aspects of warfare.

Ares is often depicted as a more chaotic and less favored deity, known for his aggressive nature and less favorable reputation among other gods and mortals in Greek mythology. In contrast, Mars in Roman belief was more enshrined and held in higher esteem, often associated with agricultural fertility as well as war.

The other options do not represent the god of war. Zeus is the king of the gods and ruler of Mount Olympus, Hercules is a hero known for his incredible strength and his twelve labors, and Hades rules the underworld. Each of these deities has distinct roles that do not relate to the martial attributes held by Ares or Mars.