The correct answer is B. Celsius.
The Celsius scale is a temperature scale where water freezes at 0 degrees and boils at 100 degrees at sea level. It is the most common temperature scale in use today, and is used in most countries around the world.
The Fahrenheit scale is a temperature scale where water freezes at 32 degrees and boils at 212 degrees at sea level. It is used in the United States and a few other countries.
The Kelvin scale is a temperature scale where water freezes at 273.15 degrees and boils at 373.15 degrees at sea level. It is the SI unit of temperature, and is used in science and engineering.
The Absolute scale is a temperature scale where absolute zero is the lowest possible temperature. It is defined as the temperature at which all molecular motion ceases.