The operating principle of a hydraulic press is

A. Pascal’s principle
B. Archimedes’ principle
C. Newton’s law of gravitation
D. Boyle’s law.

The operating principle of a hydraulic press is Pascal’s principle which states that Pressure applied anywhere to a body of fluid causes a force to be transmitted equally in all directions; the force acts at right angles to any surface in contact with the fluid.

Therefore, the hydraulic press is an application of Pascal’s law.