15. Two like charges: A. Attract each other B. Repel each other C. Must be neutrons D. Neutralize each other

B. Repel each other

Explanation:

Two like charges have the same sign. Example an electron with a negative charge (-e) and another electron with same charge(-e). Or a proton with a positive charge (+e) and another proton with same charge (+e). Since each of  these pair charges have the same sign, they will repel each other.

On the other hand, if the charges are opposite, ie  negative charge and positive charge, they will attract each other.

B. Repel each other