Which feature of the sea did the Greeks use to their advantage during King Xerxes' invasion?

The correct answer highlights the importance of the narrow straits, particularly in the context of Greek naval strategy during King Xerxes' invasion. The Greeks were able to utilize their knowledge of these straits to their advantage in the naval battles, notably the Battle of Salamis. The narrow passages limited the maneuverability of the larger Persian fleet, allowing the smaller and more agile Greek ships to effectively engage and outmaneuver the enemy.

This strategic positioning meant that the Greeks could capitalize on their strengths—superior seamanship and smaller, faster ships—while negating the size advantage held by the Persian navy. The topography of the waterway facilitated tactics that relied on surprise and speed, which were critical in achieving a decisive victory.

Other options, while integral to various aspects of naval warfare, did not provide the same tactical advantage as the narrow straits. The open waters of the bay and the swift currents are broader and can give advantage in different contexts, but they do not focus on the specific tactical engagement that characterized the Greek victory over Xerxes' forces. Storms in the Gulf may impact naval operations but typically introduce an element of unpredictability rather than a tactical advantage directly linked to battle strategies. Thus, the narrow straits emerge as the feature that