A decrease in temperature will affect vapor pressure by:

A. increasing the density of the gas molecules, thus making them heavier and more difficult to move around

B. decreasing the surface area of the gas molecules, thus decreasing the number of collisions occurring

C. increasing the rate of condensation

D. decreasing the average kinetic energy of the molecules, making them move slower and collide less

The correct option is D

Explanation:

Vapour pressure is the pressure exerted by vapour on it's solid or liquid form. When temperature increases, vapour pressure increases as the increase in the temperature causes the average kinetic energy of the vapour molecules to increase; this forces the molecules to collide more with each other and it's solid or liquid form.

When the temperature is reduced, the vapour molecules are relaxed and hence the average kinetic energy of the vapour molecules is reduced. When this happens, the vapour molecules move slower and collide less.

B or a I think