The correct option is A Samuel plimsoll
A load line, also called Plimsoll mark found by Samuel plimsoli, is a marking indicating the extent to which the weight of a load may safely submerge a ship, by way of a waterline limit. The purpose of the load line is to ensure that a ship has sufficient freeboard (the height from the waterline to the main deck) and thus sufficient reserve buoyancy (volume of ship above the waterline).