Which of the following statements regarding polyploidy is true?

• A. Polyploidy is when an organism's nucleus contains three or more sets of chromosomes.
• B. Autopolyploids are polyploids whose karyotype is made up of chromosomes from a single species.
• C. Allopolyploids are polyploids with chromosome sets from two or more species.
• D. All of the above

Answer: (D)