The purpose of not using these models together is to show that plant cells have chloroplasts, while animal cells do not. Hence the correct option is d.
The use of these models together serves the purpose of illustrating various aspects of plant and animal cells, emphasizing their structural differences. The models aid in showcasing the presence of a rigid cell wall in plant cells, distinguishing it from the more flexible structure of animal cells.
Additionally, they highlight variations in cell shape, emphasizing the uniqueness of plant and animal cellular structures. The absence of chloroplasts in animal cells, a feature exclusive to plant cells, is also depicted, contributing to a comprehensive understanding of cellular distinctions between these two biological entities. Hence the correct option is d.