What type of cargo is loaded and unloaded by driving it on and off a vessel?

The correct choice pertains to RO-RO cargo, which stands for "Roll-On/Roll-Off" cargo. This method of cargo handling involves loading and unloading vehicles, such as trucks and cars, directly onto a vessel via ramps. This is especially efficient for transporting wheeled cargo because it allows for quick and easy access to the cargo space. The vehicles can simply be driven on and off the vessel, minimizing the need for cranes or other loading equipment.

In contrast, bulk cargo typically refers to loose materials such as grains, coal, or minerals that are loaded and transported without packaging. This type cannot be driven onto or off the vessel but requires specialized handling equipment. Container cargo involves standardized containers that are lifted on and off the ship using cranes; this process involves a different mechanism entirely, as containers are not driven on. Liquid cargo consists of commodities like oil and chemicals that are transferred via pipelines or pumps and also do not involve driving vehicles on and off the ship. Each of these cargo types utilizes distinct handling methods that are not compatible with the RO-RO process.