Answer is A) The connecting rod and crankshaft
The connecting rod is attached to a piston, which is pushed up and down due to pressure created by a heat-generating reaction in its chamber. As the piston is moved by the this pressure, its connecting rod, attached to the crank shaft, rotates the crank shaft. As the crankshaft completes a rotation, the piston is compressed to its original spot, again due to the attached connecting rod, and the cycle repeats.
