Molecules would move the fastest when

A.the temperature is increased
B.the molecule is bigger
C.the energy is decreased
d.the temperature is decreased

Temperature is defined as the average Kinetic energy of molecules. So if average KE increases , then....

Molecules would move the fastest when the temperature is increased.

Explanation: The movement of molecules is influenced by the kinetic energy they possess. Kinetic energy increases with an increase in temperature. When the temperature is raised, the molecules gain more energy, causing them to move faster and increase their average speed. As a result, their kinetic energy and the collisions between the molecules become more frequent and intense. So, option A is the correct answer.