A、When a vessel is alongside the wharf, it’s necessary for the ship to keep a 24-hour deck watch to guarantee the safety of the ship and the cargo. B、When a vessel is alongside the wharf, t’s necessary for the ship to keep a 24-hour gangway watch to guarantee the safety of the ship and the cargo. C、When a vessel is alongside the port, it’s necessary for the ship to keep a 24-hour deck watch to guarantee the safety of the ship and the cargo. D、When a vessel is alongside the port, it’s necessary for the ship to keep a 24-hour gangway watch to guarantee the safety of the ship and the cargo.