Global air circulation cells move air

a) from the equator to the poles

b)
clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.

c) randomly

d)
from low pressure to high pressure

e)
in different directions at different latitudes

Global air circulation cells move air "clockwise in the Northern hemisphere and counterclockwise in the Southern hemisphere".

Option B

Explanation:

Global circulation is defined as the global connection of winds, through which the requisite heat transport  from tropical latitudes to polar latitudes carried out. Each hemisphere comprises with three cells, such as Hadley, Ferrel and Polar cell, air circulation take place in this through the complete depth of the troposphere.

The worldwide circulation cells allow passage of air in clockwise pattern in the northern hemisphere while in southern hemisphere circulate in counter-clockwise pattern from equator to poles but in different directions and at different latitudes.

the real answer is b. scintillation counter