An insulating pipe of cross-sectional are a A contains an electrolyte which has two types of ions: their charges being $-e$ and +2e.  A potential difference applied between the ends of the pipe result in the drifting of the two types of ions, having drift speed = v (-ve ion) and v/4 (+ve ion).
Both ions have the same number per unit volume = n. The current flowing through the pipe is

• A

  $\frac{1}{2}\mathrm{nevA}$

• B

  $\frac{1}{4}\mathrm{nevA}$

• C

  $\frac{5}{2}\mathrm{nevA}$

• D

  $\frac{3}{2}\mathrm{nevA}$