Six charges q ,q q, -q , -q ,q are to be arranged on the vertices of a regular hexagon PQRSTU such that the electric field at centre is double the field produced when only charge 'q' is placed at vertex R. The sequence of charges from P to Q is
A) q . -q , q ,q -q , -q B)q ,q q,-q,-q ,-q
C)-q, q , q , -q , -q , q C)-q , q , q , q , -q , -q