The E-Field at Point P for Each of the Following

The E-field at point P for each of the following is zero except for the case of

A) any two-dimensional regular polygon (such as an equilateral triangle or a square) , P at the geometric center, an identical charge at each vertex.
B) any three-dimensional regular solid (such as a cube or a tetrahedron) , P at the geometric center, an identical charge at each vertex.
C) any two-dimensional regular polygon with an even number of sides (such as a square or hexagon) , P at the geometric center, identical charges (of either sign) at each of a pair of vertices opposite each other.
D) Hold it! There are no exceptions.