Odd Man Out

This is the only group containing two vowels.

All except Alligator have protective shells.

In all other groups, the numbers are in the ratio 2 : 3 : 6 : 4

This is the only group containing two vowels.

All except Direct are synonyms.

In the other groups, there is a gap of 2 letters between first and second letters also a gap of 3 letters between second and third letter.

All except Wife are elderly people.

Each of the numbers except 56, can be expressed in terms of power of 2.

All except Nitrogen are used as fertilizers.

All except Banana are juicy fruits.