Which of those four words measures something that is of a different form of quantity than the other three.
Kilogram is the word that measures a different form of quantity than the other three. Inch, centimeter, and yard all measure length, whereas kilogram measures weight or mass.
Which word does not belong to others?

Inch
Kilogram
Centimeter
Yard Yard. All of the other words contain the letter "i" except "Yard".