The correct answer is A. The balloon has a static electric charge from rubbing Sandy's hair.
Step-by-step explanation:
In physics, the static electricity occurs as one surface or element is charged due to contact or friction, which leads to an imbalance in charges. In the case presented, the ballon and Sandy's hair have static electricity because they have been rubbed with each other. This also means, the electrical charges in both had changed and this makes the balloon be negatively charged and the hair positively charged or vice-versa which causes each of these objectes to stick to certain surfaces and to repel others. According to this, the reason the ballon is now sticking to the wall is "The balloon has a static electric charge from rubbing Sandy's hair".