INLAND ONLY While underway in a harbor you hear a vessel sound a prolonged blast. What does this signal indicate?

Correct Answer: Option D — is moving from a dock

33 CFR 83.34(g) (Inland Rule 34) specifies that a vessel nearing a bend or an area of a channel where other vessels may be obscured by an intervening obstruction, or a vessel moving from a dock or berth, shall sound one prolonged blast to alert other vessels in the vicinity.