When no flow occurs through the venturi meter, the indicator on the differential-pressure gage is straight up and indicates a Δp of zero. When 5 cfs of water flows to the right, the differential-pressure gage indicates Δp = +10 psi. If the flow is now reversed and 5 cfs flow to the left through the venturi meter, in which range would Δp fall? 

(a) Δp < −10 psi, 

(b) −10 psi < Δp < 0, 

(c) 0 < Δp < 10 psi, or 

(d) Δp = 10 psi?