Answer:
The balloon gets charged with electrostatic energy
Step-by-step explanation:
We can say that all the matter is composed by atoms that are charged particles as they are formed by a nucleus and a cloud of electrons. Usually matter is neutral this means that they have the same number of positive and negative charges.
Now when the balloon is rubbed with a wool cloth, some of the electrons that are in the wool, pass to the balloon, making it more negative and then it has the capacity to attract other objects. Then you are charging the ballon with the negative charge of the electrons, and this is known as electrostatic energy.