Question

what makes this individual’s karyotype not normal? a missing sex chromosome; an extra autosome; a missing autosome; an extra sex chromosome

Explanation:

A normal human karyotype has 46 chromosomes (22 pairs of autosomes and 1 pair of sex chromosomes, XX or XY). In this karyotype, looking at the autosomes (non - sex chromosomes), there's an extra autosome (one of the autosomal pairs has three chromosomes instead of two). Sex chromosome issues would involve the X/Y chromosomes, but here the abnormality is in autosomes. So the correct reason is an extra autosome.

Answer:

B. An extra autosome