Which of the following is not a sex-linked trait?

Tjio and Levan's contribution is very significant because they

Select the incorrect statement from the following.

$Statement A$: For a particular character in an individual,each gamete gets only one allele.
$Statement B$: Chromatids of a chromosome split (separate) and move towards opposite poles during anaphase of mitosis.

Identify the correct and incorrect statements from the following:
$(1)$ Mendel is considered the father of modern genetics.
$(2)$ Down's syndrome is a sex-linked chromosomal disorder.
$(3)$ Sickle cell anemia is an example of point mutation.
$(4)$ Color blindness is a hereditary trait.
$(5)$ Triploid female flies are found in Drosophila.

Which of the following statements are correct?
$i$. $X$ chromosome has a large amount of euchromatin.
$ii$. Heterochromatin is genetically inert.
$iii$. Both $X$ and $Y$ chromosomes are homologous.
$iv$. Crossing over does not take place in sex chromosomes in females.
Choose the correct option.