Option (c) Avogadro's hypothesis
Explanation
By definition of vapour density of a gas ,we know
Vapour density (D)
= mass of 1L gas at NTP,/mass of 1L Hydrogen at NTP
We know molecular wt M=2D
And by actual experiment the mass of 1L Hydrogen at NTP is 0.089g
So (M×0.089)g hydrogen occupies 1L at NTP
So 1gmole or Mg hydrogen will occupy 2/0.089=22.4L at NTP