Hydrostatic pressure is caused by which factor?

• A. Fluid motion in a pipe
• B. Vacuum conditions
• C. The weight of the liquid above the point
• D. External magnetic fields

Answer: (C)

Hydrostatic pressure comes from the weight of the liquid column above the point. In a fluid at rest, each layer supports the weight of the layers above it, and that weight is transmitted throughout the fluid, creating pressure that increases with depth. The deeper you go, the more liquid sits overhead, so the pressure rises roughly as p = ρ g h. This situation is independent of any fluid motion (that would add dynamic pressure) and is not caused by vacuum or external magnetic fields. So, the factor responsible is the weight of the liquid above the point.