133.Four point charges are placed at the corners of a square with diagonal 2a as shown in the diagram. What is the total electric field at the center of the square?
(A) kq/a2 at an angle 45∘ above the +x axis.
(B) kq/a2 at an angle 45∘ below the -x axis.
(C) 3kq/a2 at an angle 45∘ above the -x axis.
(D) 3kq/a2 at an angle 45∘ below the +x axis.