Which of the following is the best reason that scientific models are used?
a. they prove scientific theories
b. they visualize things that are very complex, very large, or very small
c. they provide a concrete view of something abstract
d. they precisely mimic something in nature

The correct answer is b. Option a is incorrect because these models can demonstrate scientific theories, but they don't prove scientific theories (you would need experiments for that). Option c is incorrect because the models aren't always representing something abstract (i.e. DNA is very real, just very small). Option d is incorrect because they don't precisely mimic something in nature, but instead help us visualize something in nature that is difficult to see or comprehend.