The correct option is option 3, which states that both the charges are oppositely charged.

When two charges have opposite signs (one positive and one negative), they will experience an attractive force. This is because positive charges attract negative charges and vice versa. The magnitude of the force will depend on the distance between the charges and the magnitude of the charges themselves.

Option 1 states that both charges are positive, which would result in a repulsive force between them. Like charges repel each other, so this statement is incorrect.

Option 2 states that both charges are negative, which would also result in a repulsive force. Again, like charges repel each other, so this statement is also incorrect.

Option 4 states that all the options 1, 2, and 3 are correct, but this is incorrect as option 1 and 2 are incorrect.

Hence, the only correct option is option 3, which explains that the existence of a positive force between two charges occurs when they are oppositely charged.