Refractive index of a petrofuel which is the ratio of velocity of light in air to its velocity in the petrofuel gives an indication if its_________________?

Refractive index of a petrofuel which is the ratio of velocity of light in air to its velocity in the petrofuel gives an indication if its_________________?

A. Molecular weight
B. Aromatics content
C. Both A. & B.
D. Neither ‘a’ nor ‘b’