Final answer:
A sex-linked trait is located on a sex chromosome, typically the X chromosome. This results in different inheritance patterns for males and females, with males more likely to express recessive X-linked traits.
Step-by-step explanation:
A sex-linked trait is a trait that is A) Located on a sex chromosome. Sex chromosomes are the X and Y chromosomes that determine the sex of an organism, and a sex-linked trait refers to a trait controlled by a gene located on one of these chromosomes. In humans and many other species, females have two X chromosomes (XX), whereas males have one X chromosome and one Y chromosome (XY). This difference in sex chromosome composition means that certain traits are sex-linked, predominately associated with the X chromosome since the Y chromosome carries fewer genes.
X-linked traits are more commonly discussed in genetics because the X chromosome carries more genes than the Y chromosome. Inheritance patterns for X-linked traits can result in different expressions of the trait in males and females. Since males have only one X chromosome, they are more likely to express recessive X-linked traits if the allele is present, while females with two X chromosomes typically require two copies of the recessive allele to express the trait.