What Is the Purpose of the Minimal Erythema Dose (MED)

What is the purpose of the minimal erythema dose (MED) test?

A) To calibrate the UV light with the wavelength of the skin's radiation
B) To determine the time at which a mild sunburn is produced
C) To determine the depth of penetration of the UV light
D) To calculate the dosage required to raise the temperature of the skin 2°C