Two point charges are separated by some distance as shown. The charge of the first is positive. The charge of the second is negative and its magnitude is twice as large as the first. Is it possible find a place to bring a third charge in from infinity without changing the total potential energy of the system?

a. YES, as long as the third charge is positive
b. YES, as long as the third charge is negative
c. YES, no matter what the sign of the third charge
d. NO