Two Point Charges of Unknown Magnitude and Sign Are a Distance

Multiple Choice

Two point charges of unknown magnitude and sign are a distance d apart.If the electric field strength is zero at a point between them on the line joining them,you can conclude that

A) the charges are equal in magnitude but opposite in sign.
B) the charges are equal in magnitude and have the same sign.
C) the charges are not necessarily equal in magnitude but have opposite signs.
D) the charges are not necessarily equal in magnitude but have the same sign.
E) there is not enough information to say anything specific about the charges.