Final answer:
Gallons are incommensurable with kilograms because gallons measure volume, whereas kilograms measure mass. Conversion factors enable the translation between different units of weight or mass.
Step-by-step explanation:
The unit that is incommensurable with kilograms is gallons. Kilograms are a unit of mass in the International System of Units (SI), while gallons are a unit of volume in the English system. Tons, ounces, and pounds are all units of weight or mass and can be converted to kilograms through the appropriate conversion factors. For example, one kilogram is equivalent to approximately 2.20462 pounds, and there are 16 ounces in a pound. The conversion factor between pounds and kilograms can provide the specific ratio to make this conversion.