The Celsius temperature is a/an

1. approximate temperature
2. absolute temperature
3. specific temperature
4. relative temperature

Celsius measurement follows an interval system and not a ratio system. It means that it is a relative scale and not an absolute scale.

For example, while 10°C and 20°C have the same interval difference as 20°C and 30°C the temperature 20°C is not twice the air heat energy as 10°C. Degrees Celsius is a useful interval measurement but does not possess the characteristics of ratio measures like weight or distance.

The correct option is D.