Crocodile : Lizard : Chameleon — Select the option that belongs to the same zoological class (reptiles) as the given trio.

Introduction / Context:
Crocodile, lizard, and chameleon belong to the class Reptilia. The task is to select another reptile from the options, rejecting mammals and birds.

Given Data / Assumptions:

• The category is reptiles.
• Options contain mammals, a bird, and a reptile.
• We must choose the organism that is a reptile.

Concept / Approach:
'Snake' is a reptile, aligning with the set. 'Whale' and 'lion' are mammals; 'hen' is a bird. Therefore, only 'Snake' keeps the zoological class consistent.

Step-by-Step Solution:
1) Determine the class: reptiles.2) Evaluate options; pick the reptile.3) Select 'Snake'.

Verification / Alternative check:
Basic zoology confirms the class membership distinctions.

Why Other Options Are Wrong:

• Whale/Lion: Mammalia.
• Hen: Aves.
• None of these: Incorrect because 'Snake' fits.

Common Pitfalls:
Associating crocodiles with amphibians; they are reptiles.

Final Answer:
Snake