Whale is Mammal and all others are Reptiles.

The sum of digits of 79, 44 and 55 is even, whereas the sum of digits of 72 is odd.

In options A, C and D:

1^st Alphabet + 1 = 2^nd Alphabet

2^nd and 3^rd alphabets are consecutive

Whereas, option B does not follow this pattern.

Group Captain is a rank of Indian Air force, whereas the other three are ranks of Indian Coast Guard.

In options (a), (c) and (d) on dividing sum of 1^st and 3^rd digit by 2^nd digit we get the result as 2.

Like, in option (a): 753 => (7 + 3)/5 = 2 & 987 => (9 + 7)/8 = 2

Similar, is the case with options (c) and (d), but option (b) does not follow this logic and so is the odd one out among the given options.

Options (a), (b) and (d) are eye problems & diseases. Whereas, option (c) is problem in the lungs.

Except ’35 – 51’, in all other pairs, 2^nd number is reverse of the first number.

Only in STU, all alphabetical letters are continuous according to English alphabetical series.

Except, ‘Plant’, All other options are part of a plant.

Only ‘C++’ is a programming language. Others are operating systems.

Going through options:

B + 2 = D, D + 2 = F

G + 2 = I, I + 2 = K

L + 1 = M, M + 2 = O

O + 2 = Q, Q + 2 = S