Which of the following is an example of a polygenic trait?

• A. Height
• B. Blood type
• C. Eye color determined by a single gene
• D. Hair texture

Answer: (A)

Polygenic traits arise when many genes each make a small contribution to a phenotype, producing continuous variation rather than distinct categories. Height demonstrates this clearly: numerous genes add up to determine stature, and environmental factors like nutrition can modulate it, so people show a wide range of heights rather than a few specific kinds. The other options are described in a way that points to single-gene inheritance—blood type is set by one gene with a few alleles and yields discrete groups, while eye color is described as controlled by a single gene. Hair texture can involve multiple genes as well, but height is the classic example that best illustrates polygenic inheritance.