Answer:
I think that Gravity is not considered a gas but it can at the same time
Explanation:
Gasses are affected by gravity, as above video will prove. ... Yes, there is a attractive force between the gas molecules and gravity !
The rest are for sure gases
Answer: Gravity.
Explanation: Gravity is what holds the earth's atmosphere to it (which is a mixture of gases). For example, Moon doesn't have an atmosphere only because of a weak gravitational field but that doesn't mean that gravity can be considered as a gas.
Other options (Oxygen, Hydrogen and Helium) are all gases.
