What outcome can result from nondisjunction?

Nondisjunction refers to the failure of homologous chromosomes or sister chromatids to separate properly during cell division. This error can lead to gametes that have an abnormal number of chromosomes. When these gametes unite during fertilization, it results in offspring with either an extra chromosome (as in Down syndrome, which involves an additional 21st chromosome) or a missing chromosome (as seen in Turner syndrome, where an individual is missing one of the X chromosomes).

This incorrect separation during cell division disrupts the normal chromosome count, leading to various genetic disorders, which is why extra or missing chromosomes is the direct outcome of nondisjunction. The other options do not accurately reflect the consequences of this chromosomal misdistribution; increased fertility, normal chromosome count, and improved health status are not results you would expect from nondisjunction.