Analogy completion — choose the best word to complete the relationship: tadpole → frog → amphibian :: lamb → sheep → __

Introduction / Context:
This analogy assesses taxonomic classification and life-stage recognition. A tadpole matures into a frog, and the adult frog belongs to the class amphibian. Similarly, a lamb matures into a sheep, and the adult sheep belongs to a broader biological class you must identify.

Given Data / Assumptions:

• Tadpole → frog (life stage transition).
• Frog → amphibian (class-level category).
• Lamb → sheep (life stage transition).
• Sheep → __ (class-level category should parallel amphibian).

Concept / Approach:
Maintain the pattern 'juvenile → adult → class.' The correct completion is the biological class to which a sheep belongs. Sheep are warm-blooded vertebrates that nurse their young and have hair/wool, placing them in the class Mammalia (mammals). Therefore the best parallel to 'amphibian' is 'mammal.'

Step-by-Step Solution:

Verification / Alternative check:
Check competing choices: 'animal' is too broad (kingdom-level). 'Farm' is not a taxonomic level. 'Wool' is a product, not a class. 'Herbivore' is a diet category, not a biological class. 'Mammal' uniquely mirrors 'amphibian' in taxonomic rank (both are classes), confirming the fit.

Why Other Options Are Wrong:

• animal: an overly broad kingdom label; not parallel to 'amphibian'.
• farm: not a biological category.
• wool: a material produced, not a classification.
• herbivore: diet-based group, not a class.

Common Pitfalls:
Selecting a true statement that breaks the analogy's level of abstraction. Always match the taxonomy rank used in the first half of the pattern.

Final Answer:
mammal