utilizing oil; because oil cannot be compressed, pressure is placed upon the oil, resulting in a lifting motion
The use of oil is the only answer that accurately describes the motion and mechanics of hydraulic jacks. Though the other answers correctly describe the purpose of a jack (to increase height), they do not mention oil or compression in the function of a jack.
B using a pulley system to lift items
C using a corkscrew-like effect to function
D pressing together two interfacing parts to increase height