Concept:Morphological variations are physical and structural differences that are visible in an organism, while physiological variations are internal functional or chemical differences.
Explanation:In humans, colour, fingerprints, and size are examples of morphological variation because they are clearly visible and are related to body structure or appearance.
The ability to taste
PTC depends on a specific taste receptor and is detected through a chemical response in the body.
This makes it a physiological or biochemical trait, not a structural or visible morphological trait.
Hence, the trait that does not qualify as a morphological variation in humans is the ability to taste
PTC.
The other three options are all physical features that can be seen and compared directly.
Answer:A. Ability to taste PTC