Concept:Differences in physical traits between individuals of the same species are known as variation.
Explanation:The diagrams show different comb shapes in domestic fowl, including single, pea, rose, and walnut combs.
All these combs belong to the same species of bird but appear in several distinct forms.
This occurrence of different forms of a single characteristic among members of a species is called variation.
Inheritance refers to the passing of traits from parents to offspring, which is not directly shown here.
Cell theory and courtship behaviour are unrelated to the comb types.
Therefore, the comb types displayed illustrate variation.
Answer:A. variation
