**Core Concept**
The question is testing the understanding of the basic principles of photometry, specifically the unit of light emitted from a surface. The correct answer is related to the measurement of light intensity.

**Why the Correct Answer is Right**
The unit of light emitted from a surface is **Lumen (lm)**. This unit is used to measure the total amount of visible light emitted from a surface in all directions. Lumen is a measure of the luminous flux, which is the rate at which light is emitted from a source. This unit is essential in photometry, particularly in the design and evaluation of lighting systems.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a unit of light measurement. It is a term used in other contexts, such as a unit of mass or a unit of time.
**Option B:** This option is not a unit of light measurement. It is a term used in other contexts, such as a unit of energy or a unit of power.
**Option C:** This option is not a unit of light measurement. It is a term used in other contexts, such as a unit of electric current or a unit of electric charge.

**Clinical Pearl / High-Yield Fact**
Lumen is often confused with Lux (lx), which is a unit of illuminance, measuring the amount of light falling onto a surface. While Lumen is a measure of light emitted, Lux is a measure of light received.

**Correct Answer: C. Lumen (lm)**