The correct answer is C. Kelvin.
The Kelvin scale is the only absolute temperature scale. It is based on the triple point of water, which is the temperature and pressure at which water can exist in equilibrium in the liquid, solid, and gaseous states. The Kelvin scale is also known as the thermodynamic temperature scale.
The Celsius scale is a temperature scale where water freezes at 0 degrees and boils at 100 degrees. The Fahrenheit scale is a temperature scale where water freezes at 32 degrees and boils at 212 degrees.
Both the Celsius and Fahrenheit scales are relative temperature scales. This means that they are based on the freezing and boiling points of water, which are not absolute values. The Kelvin scale, on the other hand, is an absolute temperature scale. This means that it is based on the triple point of water, which is an absolute value.
The Kelvin scale is used in science and engineering because it is more precise than the Celsius and Fahrenheit scales. The Kelvin scale is also used in the International System of Units (SI).