The correct option is C Atmospheric pressure is measured with the help of an instrument called a barometer.
Atmospheric pressure is an important factor in terms of weather phenomenon. It is not uniform across the globe. Thus, it helps in the formation of pressure gradients among various places. Atmospheric pressure is measured with the help of an instrument called a barometer. It is expressed as the millibars. At the sea surface, the average atmospheric pressure is around 1,013.2 millibars.