SI Base Unit for Temperature

Steps:

• Identify the SI system, which defines seven base units for fundamental quantities.
• Recall that temperature is a base quantity in SI.
• Note the base unit for temperature is the kelvin, not derived from others.
• Confirm the official symbol for kelvin is K, per international standards.

Why B is correct:

• The kelvin (K) is the SI base unit for thermodynamic temperature, as defined by the International System of Units (SI Brochure).

Why the others are wrong:

• A. C: Symbol for coulomb, the SI unit of electric charge.
• C. °C: Symbol for degree Celsius, a derived unit not base SI for temperature.
• D. K: Duplicate of B, but listed separately; correct symbol is K for kelvin.

Final answer: B