Answer: Option (c) is the correct answer.
Step-by-step explanation:
As density is mass divided by volume.
Mathematically, Density =

So, more is the mass of a substance more will be its density but if volume is low then density will also have a low value.
Molar mass of neon is 20 g/mol.
Molar mass of
is 44 g/mol.
Molar mass of
is 70.9 g/mol.
Since,
molecule has the highest mass. Therefore, its density will also be high.
Thus, we can conclude that out of the given options
gas has the highest density.