What sound signal is indicated for an aground vessel?

Answer: B — Three bell claps followed by a whistle

The appropriate sound signal for an aground vessel is indeed three bell claps followed by a whistle. According to the COLREGs, this specific signal is designated for vessels that are grounded or unable to move. The three bell claps are meant to indicate the situation of being aground, while the whistle serves as an additional warning signal to other vessels in the vicinity. This sound signal is critically important for safety as it notifies other vessels that the aground vessel is not able to maneuver or take action to avoid collisions. The combination of bell claps followed by a whistle communicates a clear message about the vessel's status to nearby traffic, helping to prevent accidents and ensure maritime safety. It's essential for mariners to understand and recognize these sound signals to maintain safe navigation and avoid misunderstandings on the water.