Which of the following is the SI unit used to measure mass?

• A. kilogram
• B. liter
• C. gram
• D. pound

Answer: (A)

Verified step by step guidance

1. Understand that the International System of Units (SI) defines standard units for various physical quantities, including mass.
2. Recall that the base SI unit for mass is the kilogram, which is the only SI unit among the options provided.
3. Note that the gram is a derived unit in the SI system, equal to one-thousandth of a kilogram (1 gram = 10^{-3} kilograms), but it is not the base SI unit.
4. Recognize that the liter is a unit of volume, not mass, and the pound is a unit of mass used primarily in the imperial system, not SI.
5. Conclude that the correct SI unit for measuring mass from the given options is the kilogram.