During pregnancy, a cell undergoes what appears to be a normal mitotic nuclear division. However, two daughter cells with 2n-1 and 2n+1 complement of chromosomes are produced, causing a population of cells to be abnormal. Which of the following events is most likely responsible for this disorder?
A) Two sister chromatids did not separate into the proper daughter cells during anaphase.
B) Homologous chromosomes were sorted incorrectly during prophase.
C) The protein structure of nonkinetochore microtubules was defective, and incorrectly shortened during anaphase.
D) The cleavage furrow did not completely separate the two daughter cells.
Answer: A) Two sister chromatids did not separate into the proper daughter cells during anaphase.