Actually, I strongly believe it is a switch.
Gas molecules have either very weak bonds or no bonds at all, so they can move freely and quickly. Because of this, not only will a gas conform to the shape of its container, it will also expand to completely fill the container.
It might be c, because he came up with the plum pudding model. or it might be that atoms of the same element are identical, but that's not true cuz ions are different and isotopes are different.
<span> the answer to your question is Troposphere</span>