Final answer:
Model A: Nesting dolls with identical shapes, where smaller dolls fit inside larger ones.
Step-by-step explanation:
The best model that demonstrates the levels of organization in plants and animals using nesting dolls is Model A: Nesting dolls with identical shapes, where smaller dolls fit inside larger ones. This model represents the hierarchical structure of living organisms, where each sublevel is more similar. Just like nesting dolls, smaller structures fit inside larger ones in a coordinated manner, with each level building upon the previous one.