X-linked traits are primarily expressed in

A. adulthood.

B. females.

C. people with an extra sex chromosome.

D. males.

male

Explanation:

All genes located on the sex chromosomes are said to be sex-linked and therefore are transmitted together with those that determine sex. The traits determined by these genes are inherited and expressed in both the male and female primarily in adulthood. The X-linked traits are expressed primarily in males because they receive only one copy of the X chromosome, if that chromosome carries the trait or disorder then it will be expressed, while in females, only if the two copies of the X chromosome carries the trait or disorder will be expressed, because of this females are normally carriers. All this especially for X-linked recessive inheritance.