The correct answer is a. copies of the same chromosome.
Explanation:
The two versions of a trait, or alleles, are located on homologous chromosomes. These are paired chromosomes, one inherited from the mother and one from the father. Each allele carries the instructions for a specific variation of the trait. For example, if the trait is eye color, one allele might code for blue eyes and the other for brown eyes.
Why other options are incorrect:
b. two different chromosomes:
While different traits are located on different chromosomes, the two versions of the same trait are always on homologous chromosomes, meaning they are paired copies of the same chromosome.
c. sex chromosomes:
Sex chromosomes (X and Y) determine sex. While they carry genes for some traits, they aren’t the only chromosomes involved in determining traits. Any chromosome can carry genes for various traits.
d. any chromosome:
This is incorrect because the two versions of a trait are specifically located on copies of the same chromosome, not just any chromosome.