Verbal Reasoning - Classification

In all other groups, the first and second as well as the third and fourth letters are consecutive.

In all other groups, first and third letters as well as fourth and second letters are alternate.

In all other groups, the first, second and third letters are respectively two, four and six steps ahead of the second, third and fourth letters respectively.

In all other groups, the first letter is a vowel followed by three consecutive letters.

In all other groups, the number of letters skipped between two consecutive letters increases by one from left to right.