Recall that the International System of Units (SI) defines seven base units from which all other units are derived.
Identify the SI base units relevant to the options: meter (m) is the SI base unit for length, second (s) is the SI base unit for time, and kelvin (K) is the SI base unit for temperature.
Recognize that the liter (L) is a unit of volume, which is not an SI base unit but rather a derived unit based on the cubic meter (m³).
Understand that the liter is commonly used in everyday measurements but is not part of the official SI base units.
Conclude that among the given options, liter is NOT an SI base unit.