In the context of SI units, what does 'cd' stand for?

In the context of SI (International System of Units) units, 'cd' stands for 'candela,' which is the unit of luminous intensity. The candela measures the power emitted by a light source in a particular direction, emphasizing the human visual perception of brightness. It is one of the seven base units in the SI system and plays an essential role in various applications, including lighting design and photometry.

The other options refer to different units: 'coulomb' is the unit of electric charge, 'centimetre' is a unit of length, and 'cubic decimetre' is a unit of volume. Each of these units serves its specific purpose within the various fields of science and engineering but does not relate to the measurement of luminous intensity like the candela does. Understanding the correct SI unit is crucial for clarity in scientific communication and application.