Concept:The shape of a domestic fowl's comb is an inherited physical characteristic.
Explanation:Different breeds of domestic fowl show distinct comb types, such as single, rose, pea, and walnut combs.
These differences are passed from parents to offspring through genes.
Environmental conditions, physiology, or morphology can affect the appearance of the comb but do not determine the basic comb type.
Since the variety of comb shapes follows patterns of inheritance, the factor responsible is genetics.
Answer:B. genetics
