What should the student add to stage 3 to complete the model? A. Add chromosomes unraveling to small, thin strands.
B. Add chromosomes exchanging information for increased variety.
C. Add chromosomes pairs being pulled toward opposite poles of the cell.
D. Add a plate in the midline of the cell to show two new cells forming.

The correct answer is option A. "producing a litter of puppies by mating two dogs of different breeds".

Explanation:

Hybridization has been applied in plants and animal breeding looking to enhance the characteristics of the organism in the next generation. When hybridization allows to increase the hybrid vigor of the offspring it is called heterosis. An example of heterosis is producing a litter of puppies by mating two dogs of different breeds. Dog's breeding sometimes produces hybrids of two different pure breeds such as the Goldendoodle (a Golden Retriever mated with a Poodle).