The basic metric unit is the metre.
meters
The ISO length unit to use would be the cementer.
Meters are used as the unit for length in most countries, but some, such as the United States, use a different system of measurement.
Units of length, such as mm, are used for this.
I would expect it would be centremetres.
It's SI unit is meters
You could measure the length of a lunchroom in feet or meters, depending on which unit of measurement you prefer to use.
miles or kilomiters
Kilometers are a unit of length, used to measure distance.
If not use the standard unit, you won't get correct answers when calculating.
A meter.
The centimeter is a unit of length.