If two balloons repel each other, they must have the same type of electrical charge. Therefore, the correct answer is:
• positive and positive
or
• negative and negative
Since the answer choices do not explicitly include both types of charges for repulsion, it suggests that they could both be positive or both be negative, but not specifically stated. If you had to choose from the given options, you would infer that both are the same charge type (either both positive or both negative) since they repel each other.