Down syndrome is linked to which specific chromosome abnormality?

Down syndrome is specifically linked to the presence of an extra copy of the 21st chromosome, a condition known as Trisomy 21. This genetic anomaly leads to the typical characteristics associated with Down syndrome, including distinct physical features and a range of developmental challenges. The extra 21st chromosome can arise from an error in cell division during the formation of eggs or sperm, resulting in a total of three copies of chromosome 21 instead of the usual two.

Understanding this genetic basis is crucial for early diagnosis, intervention strategies, and support for individuals with Down syndrome. The other options suggest different chromosomes, none of which are associated with Down syndrome, reinforcing the need for precise knowledge regarding genetic conditions and their chromosomal associations.