Answer:
a) centimeter
Explanation:
The following would be used to measure the length of a pencil - centimeter
Length is always measured in units like millimeter, centimeter or meter.
Deciliter is a unit to measure liquids.
Kilogram is a unit to measure weight of things.
Square centimeter is a unit that defines area. When two values with unit centimeter are multiplied, we get square centimeter or area.
So, the answer will be centimeter.