Symbiosis National Aptitude Test SNAP 2013 Paper

Difference between alphabetical positions of N and O = 1 = difference between 2 and 3
Difference between alphabetical positions of O and R = 3 = difference between 3 and 6.
Similarly, for REST,
difference between R and E = 13,
difference between E and S = 14
and difference between S and T = 1
So, only option (c) is right one.