Final answer:
The correct answer is 'B) g/L' as it is a derived unit of density and not a base unit of the metric system or SI units.
Step-by-step explanation:
The base units of the metric system (SI units) include units such as the meter (m) for distance, the kilogram (kg) for mass, and the second (s) for time. These units are defined without reference to other units and are used in scientific measurements. Among the choices provided, gram (g) is a base unit for mass, and liter (L) is a derived unit for volume (one cubic decimeter). However, gram per liter (g/L) is a derived unit of density, not a base unit. Therefore, the correct answer is 'B) g/L'.