Three objects are brought close to each other, two at a time. When objects A and B are brought together, they attract. When objects B and C
are brought together, they repel. From this, we conclude that (a) objects A and C
possess charges of the same sign. (b) objects A and C possess charges of opposite sign.
(c) all three of the objects possess charges of the same sign. (d) one of the objects is
neutral. (e) we need to perform additional experiments to determine information
about the charges on the objects.