A science class is breeding guinea pigs for a heredity project. Both the male and female parent guinea pigs have black fur. The first two litters of
offspring they produced all had black fur. In the third litter, two offspring with white fur were born. The students made the following model to show the
inheritance pattern they thought was happening in their project.
The students made a mistake in their model.
Which of the following models shows how the students should revise their original model to explain the results of all three litters from the same two
parents with black fur?