Which of the following describes Pascal's principle in fluid mechanics?

Pascal's principle, also known as Pascal's law, states that when a change in pressure is applied to a confined fluid, that pressure change is transmitted undiminished and equally in all directions throughout the fluid. This principle is foundational in understanding how hydraulic systems work, such as hydraulic presses and brakes, where a small force can be amplified via the application of pressure across a larger area.

The principle underscores the behavior of fluids in equilibrium and helps explain phenomena such as the operation of hydraulic systems. The other options, while related to fluid behavior, do not accurately describe Pascal's principle. For instance, the decrease of pressure with height pertains to hydrostatic pressure, the term 'turbulent' relates to the flow type, and the change in density with temperature refers to the thermal properties of fluids. None of these concepts encapsulates the essence of how pressure is transmitted in fluids, which is precisely what Pascal's principle articulates.