A charged oil drop is moving downward with a velocity V₁. As it acquires an additional charge it moves up with the velocity V₂ in the same electric field. It fall freely with a velocity V in the absence of electric field. The ratio of the charges before and after acquiring additional charge is
A. V₁ + V / V₂ − V₁
B. V₁ + V₂ / 2V
C. V − V₁ / V + V₂
D. V₂ − 2V₁ / 2V₁ + V
