Identify the underlying force behind all forms of mass movement

gravity

Explanation:

Mass movement or mass wasting is a natural process in which the unstable sediments, stones, pebbles, debris moves down the slope under the effect of gravity. These materials are disturbed by physical agents such as water, wind and others. The mass movement is responsible for mudslides or landslides.

i believe the answer is a.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.