Final answer:
Placement in the sex category is achieved through sex determination, which is the process of assigning an individual as either male or female based on their genetic and biological characteristics.
Step-by-step explanation:
Placement in the sex category is achieved through sex determination, which is the process of assigning an individual as either male or female based on their genetic and biological characteristics. In humans, sex determination is primarily determined by the presence of sex chromosomes.
The sex of an individual is determined at the moment of fertilization when the sperm carries either an X or a Y chromosome. If a sperm with an X chromosome fertilizes the egg, the resulting zygote will develop into a female. If a sperm with a Y chromosome fertilizes the egg, the zygote will develop into a male.
However, it is important to note that sex determination is a complex process and is not solely determined by the presence of sex chromosomes. There are rare cases where individuals may have atypical chromosomal patterns or variations in their hormonal and anatomical development.