Odd Man Out

All except Deliberation indicate research.

In all the other pairs, the first is present inside the second.

Swan is the only water bird in the group.

All except Tomato grow underground.

In all other groups, the first two letters are alternate letters of the alphabet, while second and third letters occupy the same positions from the beginning and the end of the alphabet respectively.

All except Hear are physical activities.

121 is the only perfect square number in the group.

All other letters occupy the even-numbered positions in the English alphabet.

Parrot, Pigeon and Crow are the Subsets of Bird. Means they are a type of bird, so rabbit is different as it is an animal.

All others denote various feeling.