Which unit is used to measure distance or displacement?

The unit used to measure distance or displacement is the metre. The metre is the fundamental unit of length in the International System of Units (SI) and serves as the primary standard for measuring linear distances in scientific contexts. It is defined based on the speed of light in a vacuum, making it a precise and universally accepted unit.

Centimetres and millimetres, while also valid units of measurement, are subunits of the metre and are generally used for measuring shorter distances. Feet, on the other hand, is used primarily in some countries like the United States and is not a standard SI unit. Therefore, the metre, as the standard unit, is the most appropriate answer for measuring distance or displacement in a consistent and widely understood manner.