Which of the following unit is not a fundamental unit:

Options

A. metre
B. litre
C. second
D. kilogram

Explanation

To determine which of the provided units is not a fundamental unit, we need to analyze each option:

1. **Meter (m)**:
- The meter is the SI unit of length.
- Length is a fundamental quantity in physics.
- Therefore, the meter is a fundamental unit.

2. **Liter (L)**:
- The liter is a unit of volume.
- Volume is not a fundamental quantity; it is derived from the fundamental quantity of length (1 liter = 1000 cubic centimeters).
- Hence, the liter is a derived unit and not a fundamental unit.

3. **Second (s)**:
- The second is the SI unit of time.
- Time is a fundamental quantity in physics.
- Therefore, the second is a fundamental unit.

4. **Kilogram (kg)**:
- The kilogram is the SI unit of mass.
- Mass is a fundamental quantity in physics.
- Thus, the kilogram is a fundamental unit.

After analyzing all the options, we conclude that the unit that is not a fundamental unit is:

**Answer: Liter (L)**