Verbal Classification

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

All except Narmada are rivers which flow into the Bay of Bengal, while Narmada flows into the Arabian Sea.

All except Sodium are radio-isotopes, while sodium is a metal.

The wing, fin, and rudder are all parts of an airplane.

All except Valley are elevated features.

An index, glossary, and chapter are all parts of a book. Choice a does not belong because the book is the whole, not a part.

All except Drone are females.

Two, six, and eight are all even numbers; three is an odd number.

All except Cortes are currencies, while Cortes is a parliament.

All except Simmer are connected with light, while simmer is a way of cooking.