Which of the following is a unit of length?

Centimeters is indeed a unit of length, and it is part of the metric system commonly used in scientific measurements. In the metric system, length can be measured in various units, including millimeters, centimeters, meters, and kilometers. Each of these units is related to one another by powers of ten, making conversions straightforward.

While milliliters is a unit of volume, used to measure the capacity of liquids; candela is a unit of luminous intensity, measuring how much light is emitted in a particular direction; and kilograms is a unit of mass, used to measure weight, none of these are applicable for measuring length. This information highlights how specific units are designated for different types of measurements in science, making centimeters the correct choice in this context.