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 ft. Which of the following arrangements of charges is possible for P, Q, R, S, T and U respectively ?

 

• A

  +,-,+,-,-,

• B

  +,-,+,-,+,-

• C

  +,+,-,+,-,

• D

  -,+,+,-,+,-