Review the responses below; then SELECT ALL the reasons why we use scientific models. a Models are used when systems are too expensive, expansive or impossible to use. b Models are always expensive. c Models allow exploring very small or very large systems. d Models help you understand complex systems.

Answer 1

The valid reasons why we use scientific models are:

a) Models are used when systems are too expensive, expansive or impossible to use.
c) Models allow exploring very small or very large systems.
d) Models help you understand complex systems.

Option b) "Models are always expensive" is not a reason for using scientific models, as models can vary in cost and are not always expensive to create or use.