Which of the following is a base unit in the metric system?

• A. gram
• B. liter
• C. meter
• D. degree Celsius

Answer: (C)

Verified step by step guidance

1. Understand that the metric system (SI units) is based on a set of base units that define fundamental physical quantities.
2. Recall the seven base units in the International System of Units (SI), which include meter (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance), and candela (luminous intensity).
3. Identify that 'gram' is a derived unit because the base unit of mass is the kilogram, not the gram.
4. Recognize that 'liter' is a derived unit of volume, not a base unit; it is related to the cubic meter.
5. Note that 'degree Celsius' is a temperature scale derived from the kelvin, which is the SI base unit for temperature, so it is not a base unit itself.