What is a karyotype used for?

A karyotype is a laboratory procedure that involves the visual examination of chromosomes in a cell sample. This technique is primarily used to identify chromosomal abnormalities, such as deletions, duplications, translocations, and aneuploidies (an abnormal number of chromosomes). By arranging the chromosomes into a standard format, scientists and medical professionals can assess the number and structure of an individual's chromosomes, allowing them to detect any genetic disorders that may be present.

This process is particularly important in prenatal testing, cancer diagnosis, and fertility assessments, as various chromosomal defects are linked to specific health conditions and developmental disorders. Therefore, the primary function of a karyotype is to look for chromosomal defects, making this option the correct answer.