Which pair of sex chromosomes designates a male?

The designation of male sex chromosomes is determined by the combination of one X and one Y chromosome, which is represented as XY. In humans and many other species, individuals with this chromosome configuration develop male biological characteristics due to the presence of the Y chromosome, which carries specific genes such as the SRY gene that triggers the development of male reproductive structures. The XY combination leads to the production of male hormones and the development of male phenotypes.

In contrast, other chromosomal combinations do not result in male designation. For instance, females typically have two X chromosomes (XX), while the other options like YY and XZ do not represent the typical chromosomal patterns understood in human sexual differentiation. Therefore, the XY combination is recognized as the defining pair of sex chromosomes that designates a male.