In water of density 1000 kg/m³ with g = 10 m/s², what is the gauge pressure 4 m below the surface?

A) 60 kPa

B) 20 kPa

C) 40 kPa

D) 80 kPa

Answer: C

Explanation: Use hydrostatic gauge pressure = ρgh for the stated idealized conditions. Substitution gives 1000 × 10 × 4 Pa, converted to kPa = 40 kPa.