Which among the following is measured by Dobson unit ?
[A]Ozone concentration
[B]Thermal conductivity
[C]Soil moisture

Ozone concentration
Dobson is the most common unit for measuring ozone concentration. One Dobson unit is the number of molecules of ozone that would be required to create a layer of pure ozone 0.01 millimetres thick at a temperature of 0 degree Celsius and pressure of 1 atmosphere.