In all pairs except (b) , first is present in second.

In all pairs except (b), first is the name of instrument which is used to measure the second.

In all pairs expert (b) , deficiency of first causes the disease in second part.

In all other pairs, second is a collective group of the first.

All others are consonants.

All others are vowels.

Expect B, all are the vowels.

All others have two vowels.

The pattern used for classification is placement of alphabets in the order (- 3, - 3, - 3). Since, option (b) dose not follow the pattern, it is odd in the group.

In all other groups, there is a gap of two letters as in the alphabet between third and fourth letters.