Final answer:
The statement about the U.S. customary system being based on the yard, pound, and gallon is true, as these units are part of the system that includes various units such as inches, feet, yards, miles, pounds, and gallons.
Step-by-step explanation:
The statement that the U.S. customary system is a system of measurements based on the yard as a unit of length, the pound as a unit of weight, and the gallon as a unit of liquid volume is true. The customary system is indeed widely used in the United States and comprises different units for different types of measurements. Customary units of length include inches, feet, yards, and miles. In terms of weight, the pound is the standard unit, and for liquid volume, the gallon is commonly used.