A condition where an organism has a chromosomal constitution of (2n - 1) is called A and it primarily arises due to B. Identify A and B from the options given below.

Step-by-step solution

A chromosomal constitution of (2n - 1) represents the loss of a single chromosome from the diploid set. This specific condition is a type of aneuploidy known as monosomy (for example, Turner's syndrome). Aneuploidy (including monosomy) arises due to the failure of segregation of chromatids during the cell division cycle. Failure of cytokinesis leads to polyploidy (an increase in a whole set of chromosomes), not monosomy. Deletion of a chromosomal segment is a structural aberration, whereas (2n - 1) represents a num