Final answer:
The SI unit for luminous intensity is the candela. It measures the perceived light power emitted in a specific direction and is related to luminous flux and luminous efficacy. Therefore the correct answer is B. Luminous intensity.
Step-by-step explanation:
The unit of luminous intensity in SI-units is the candela. Luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle. It quantifies how much light is perceived in a specific direction, which can be relevant in various applications such as in lighting design.
The candela is a base unit in the International System of Units (SI) and it is related to the lumens, which measures luminous flux, indicating the total light emitted by a source.
When considering luminous efficacy, it expresses how well a light source produces visible light using a certain amount of power, with efficacy given in lumens per Watt (lm/W).
The unit of luminous intensity in SI-units is the candela (cd). It is approximately the luminous intensity of a common candle. Luminous intensity measures the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle.