Each balloon behaved differently. Helium gas has a lower density than air. Carbon dioxide causes a balloon to expand. Balloons can be filled with different gases.
I gave my students this multiple choice question: A science teacher filled one balloon with helium gas and a second balloon with carbon dioxide. The helium-filled balloon rose to the ceiling, and the balloon filled with carbon dioxide fell to the floor. Which statement is an inference based on this demonstration?

Only one answer is correct among these 4 choices:
- Each balloon behaved differently.
- Helium gas has a lower density than air.
- Carbon dioxide causes a balloon to expand.
- Balloons can be filled with different gases.

Could you tell me which one is correct?

Helium gas has a lower density than air.