4. An incompressible fluid of density ρ is in a bucket on the elevator floor accelerating upward withacceleration a. What is the pressure difference between two points in the fluid separated by avertical distance △h? (Gravitational acceleration is g)
(A) ρa△h
(B) ρg△h
(C) ρga△h
(D) ρ(g – a)△h
(E) ρ(g + a)△h