Doubt from Gaseous State


I think that the question is incomplete please confirm.

Answer is A???

Density of gas b should be given
I m getting 6/x
Where x is density of gas b

I think the volume is given to find out the density of B

But for this mole of B should also be given

I agree with @Ankith_2020 . Answer is Option C


Anyone have theory related to it, I only konw the relation of a, b and c between them.

It is given in ncert only there are 4 columns. In 2 column eatch crystal bravais lattice is given