sound waves in air are always longitudinal because,
a)of the inherent characteristics of sound waves in air
b)air does not have modulus of rigidity
c)air is a mixture of several gases
d)density of air is very small

Dear Student ,

transverse wave travel in solids because they have  modulus of rigidity but in air their is no modulus of rigidity.
so option is B . if modulus of rigidity is absent then longitudinal waves can travel as in air.

Regards