Classification (taxonomy): Three pairs correctly match an animal with its class/family group; one pair mismatches class. Identify the odd pair.

Introduction / Context:
Basic zoological classification is commonly tested. Three pairs are correct: gnu is an antelope, elk belongs to the deer family, and shark is a fish. The outlier assigns the wrong class to the animal: a pelican is a bird, not a reptile.

Given Data / Assumptions:

• Gnu (wildebeest) → antelope.
• Elk → deer family.
• Shark → fish (cartilaginous fishes).
• Pelican → bird; not reptile.

Concept / Approach:
Validate each mapping against elementary taxonomy: bird, reptile, fish, mammal, etc. The mismatched class indicates the odd pair.

Step-by-Step Solution:

Verification / Alternative check:
Recall defining traits: pelicans have feathers, wings, beaks, and lay eggs like birds; reptiles are scaly ectotherms (snakes, lizards, etc.).

Why Other Options Are Wrong:

Common Pitfalls:
Confusing “water-associated animals” as being in the same class. Habitat does not determine taxonomic class.

Final Answer:
Pelican : Reptile