One of the pair of chromosomes responsible for determining the sex of an individual.

• A. Autosome
• B. Sex Chromosome
• C. Mitochondrial chromosome
• D. Homologous chromosome

Answer: (B)

Sex is determined by a specific pair of chromosomes that carry the genes directing sexual development. In humans, this pair is the sex chromosomes, X and Y. Having two X chromosomes typically results in female development, while having one X and one Y leads to male development. The Y chromosome contains the SRY gene, which initiates the cascade toward male differentiation; without a Y, the default pathway is female. Other chromosomes don’t determine sex: autosomes are non-sex chromosomes that carry many traits but aren’t responsible for sex determination; mitochondrial DNA is separate DNA inherited from the mother and does not govern sexual development; a homologous chromosome is simply a matching copy from each parent and is not specifically tied to sex determination.