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

Multiple Choice

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

A) any one-dimensional line, P at the geometric center, an identical charge at each end.
B) any one-dimensional line, P located between the two ends of the line, a charge at each end with the same sign and with magnitude equal to the square of its distance from P.
C) any one-dimensional line, P located between the two ends of the line, a charge at each end with magnitude equal to its distance from P.
D) any one-dimensional line, P located beyond one end of the line, a positive charge at one end with magnitude equal to the square of its distance from P, a negative charge at the other end with magnitude equal to the square of its distance from P.