Ten charges are placed on the circumference of a circle of radius $R$ with constant angular separation between successive charges. Alternate charges $1, 3, 5, 7, 9$ have charge $(+q)$ each, while $2, 4, 6, 8, 10$ have charge $(-q)$ each. The potential $V$ and the electric field $E$ at the centre of the circle are respectively (Take $V = 0$ at infinity).

• A
  $V = \frac{10q}{4\pi\epsilon_0 R}; E = \frac{10q}{4\pi\epsilon_0 R^2}$
• B
  $V = 0, E = \frac{10q}{4\pi\epsilon_0 R^2}$
• C
  $V = 0, E = 0$
• D
  $V = \frac{10q}{4\pi\epsilon_0 R}; E = 0$