Four charges are shown above. How many of them are positive?

1. One of them
2. Two of them
3. Three of them
4. All four
5. One or three of them, there's not enough information to decide

Charges 1, 2, and 4 have the same sign, while charge 3 has the opposite sign. There is either one positive charge or three positive charges.

This is consistent with our model: There are two kinds of charge, positive and negative. Like charges repel; unlike charges attract.