How does the function of a heat engine, like the one shown, illustrate the Kinetic theory of heat?

Question

anonymous · Answer

a. The Kinetic theory of heat states that kinetic energy causes particles to collide. Heat causes the fluid particles to collide with the piston particles making the piston move upward.
b. The Kinetic theory of heat states that heat is the result of the movement of particle s in a system. The piston moves upward in response to particle motion in the fluid below. 
c. The Kinetic theory of heat states that heat flows from a hotter body to a cooler body. In this case, heat flows from the heat source to the fluid and then from the fluid to the piston, causing it to move upward. 
d. The Kinetic theory of heat states that the change in internal energy of a closed system is equal to the heat added to the system. Heat added to the fluid expands the fluid and pushes it upward.

anonymous · Answer

My friend helped as well. It's A.

anonymous · Answer

thank you! :) also, some vocab help?