Choose the word which is different from the rest.

The answer is A. Gallon.

A gallon is a unit of liquid volume, while the other three options are units of mass.

• A gallon is a unit of liquid volume in the imperial and US customary systems of measurement. It is equal to 4 quarts, 8 pints, or 16 cups.
• A ton is a unit of mass in the imperial, US customary, and avoirdupois systems of measurement. It is equal to 2,000 pounds or 907.18474 kilograms.
• A quintal is a unit of mass in the metric system. It is equal to 100 kilograms.
• A kilogram is a unit of mass in the International System of Units (SI). It is the base unit of mass in the SI system and is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is a cylinder of platinum-iridium alloy that is kept at the International Bureau of Weights and Measures (BIPM) in Sèvres, France.