**The correct option is C) 20μF.**

We first find volume of big drop Volume of big drop = 64 x volume of small drop

4/3 π.R^{3} =64 x 4/3 π.r^{3}

R = 4r

Because capacitance of solid spherical body directly proportion to radius

Hence big drop capacitance = 4 x capacitance of small

Capacitance of big drop=20μF