Three Infinite Planes of Charge,A,B and C,are Vertical and Parallel

Multiple Choice

Three infinite planes of charge,A,B and C,are vertical and parallel to one another.There is a uniform electric field
To the left of plane A and a uniform electric field
To the right of plane C.The field
Points to the left and the field
Points to the right.The signs of the charges on plates A,B and C may be

A) −,−,−.
B) +,−,−.
C) +,−,+.
D) +,+,+.
E) any one of the above.