Which combination of alleles best describes a sex-linked trait?
O
O
O
heterozygous alleles
homozygous alleles
alleles that are carried on X and Y chromosomes
alleles that are carried on somatic cells

Alleles that are carried on X and Y chromosomes.

Explanation:

XX pair and XY pairs form gender.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.