The best and most correct answer among the choices provided by the question is letter C "alleles that are carried on X and Y chromosomesd. alleles that are carried on somatic cells"
In humans, red-green colorblindness is a recessive sex-linked trait. It is found on the X chromosome, not the Y. Because, males only have one X chromosome, they have a much greater chance of having red-green colorblindness. Females would have to be homozygous recessive in order to have red-green colorblindness.
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