Answer:
The rankine scale (°R)
Step-by-step explanation:
Pluto is a very cold planet whose temperature could be as low as -375 °F to -400°C (or -226 to -240°C). These extremely low temperature could make it uncomfortable using the regular metric units (kelvin, degree Fahrenheit, degree Celsius) for temperature here on earth. Hence, the need to use a higher temperature equivalent to the regular metric units.
The rankine scale (°R) which has an absolute zero based equivalent to the Fahrenheit scale (where 0°F is equal to 459.67°R). Hence, the temperature of Pluto would be between 59.67°R to 84.67°R.