What is necessary to signal a power vessel that is making way?

Answer: A — No sound signal is required

To signal a power vessel that is making way, it is correct that no sound signal is required. According to the COLREGs, vessels that are underway, which includes those that are making way, do not need to signal unless they are engaging in specific maneuvers or are involved in a situation where signaling is necessary. This is because a power vessel that is under command and moving through the water can navigate without the need for sound signals that indicate stationary status or restricted movements. In terms of the other options, each of those represents specific signals intended for particular situations. For instance, a bell signal is often used to indicate the presence of a vessel that is at anchor or restricted in its ability to maneuver. Similarly, continuous loud horn blasts and specific sound signals like one long and two short bell sounds also pertain to distinct scenarios noted in the regulations. Therefore, all these options represent required sounds for specific conditions, rather than for a power vessel simply making way, making them inappropriate in this context.