The correct option is (a) 3.21 g/s
To elaborate: Pressure differential causing fuel flow = ΔP = 15000 Pa, coefficient of discharge = Cf = 0.75, density of the fuel = ρ = 780 kg/m^3, and area of the jet = A = 0.885 mm^2. The rate of flow of fuel = Wf = A* Cf*(sqrt{2
hoDelta P}) = 0.885*0.75*10^-6*(sqrt{2*780*15000}) = 3.21*10^-3 kg/s = 3.21g/s.