Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at O is double the electric field when only one positive charge of same magnitude is placed at R. Which of the following arrangements of charge is possible for, P, Q, R, S, T and U respectively?
(A) +, -, +, -, -,+
(B) +, -, +, -, +, -
(C) +, +, -, +, -, -
(D) -, +, +, -, +, -
