What is a common unit used to express the weight of liquid cargo?

The reason why metric tons is the correct choice for expressing the weight of liquid cargo lies in its standardized use in global shipping and trade. A metric ton is a unit of mass equivalent to 1,000 kilograms or approximately 2,204.62 pounds. It provides a clear and consistent metric for measuring heavier liquid cargoes, which is important for legal and logistical purposes during transport and trade.

While pounds, cubic meters, and gallons have their uses in measuring different aspects of liquid cargo, they do not serve the same standardized role. Pounds are often used in the United States for weight but can lead to confusion when internationally dealing with cargo. Cubic meters measure volume, not weight, and while gallons can be used to describe both volume and occasionally weight in the case of water (where 1 gallon is about 8.34 pounds), they are less practical for larger maritime shipments compared to metric tons, which uniformly apply across various types of liquids and situations involving shipping. Therefore, metric tons are preferred for the clarity and uniformity they provide in maritime context.