What is the standard metric unit for measuring temperature?

The standard metric unit for measuring temperature is Kelvin. This scale is part of the International System of Units (SI), which is widely adopted for scientific measurements. The Kelvin scale is particularly important because it begins at absolute zero, the point at which all thermal motion ceases. Each Kelvin unit is equivalent in magnitude to a degree Celsius; however, the Kelvin scale does not use a degree symbol and starts at zero Kelvin (0 K), which corresponds to -273.15 degrees Celsius.

Celsius is commonly used for everyday temperature measurements, particularly in weather forecasts and cooking, but it is not the SI base unit for temperature. Fahrenheit is mainly used in the United States for everyday temperature reference and is not a metric system unit. Rankine is another temperature scale mainly used in some engineering fields, primarily in the United States, but it is not part of the metric system either.

Thus, Kelvin is the standard for scientific and metric temperature measurement, making it the correct choice in this context.