The ratio of frictional pressure drop and diameter - GATE ME '17 S1

Consider the steady flow of an incompressible fluid through two long and straight pipes of diameters d1 and d2 arranged in series. Both pipes are of equal length and the flow is turbulent in both pipes. The friction factor for turbulent flow through pipes is of the form, f=K(Re)^(−n), where K and n are known positive constants and Re is the Reynolds number. Neglecting minor losses, the ratio of the frictional pressure drop in pipe 1 to that in pipe 2, (ΔP1/ΔP2), is given by A. (d2/d1)^(5−n) B. (d2/d1)^5 C. (d2/d1)^(3−n) D. (d2/d1)^(5+n)