What is the fog signal for a power-driven vessel making way through the water?

The correct answer is that a power-driven vessel making way through the water sounds one prolonged blast followed by two short blasts as its fog signal. This signal is part of the regulations set forth by the International Regulations for Preventing Collisions at Sea (COLREGs), specifically designed to help vessels communicate their presence and movement in low visibility conditions, such as fog.

The one prolonged blast indicates that the vessel is under way and is a method for making its position known to other vessels in the vicinity. The addition of two short blasts signifies that it is a power-driven vessel, which helps differentiate it from other types of vessels, ensuring awareness and safety on the water. This specific combination of sounds is universally recognized and enhances the situational awareness of mariners navigating in restricted visibility.

The other options propose different combinations of signals that do not represent the correct fog signal for a power-driven vessel in motion. Understanding these signals and their meanings is crucial for maintaining safety at sea, especially in conditions where visibility might be compromised.