Final answer:
The best example of a state government attempting to limit migration is to require police to stop cars driven by people who may be immigrants.
Step-by-step explanation:
The best example of a state government attempting to limit migration is:
B. Requiring police to stop cars that are driven by people who may be immigrants
This measure grants authority to state law enforcement officials to question and verify the immigration status of individuals who they suspect may be in the country illegally. By requiring police to stop cars driven by people who may be immigrants, the state government is actively attempting to limit migration by subjecting individuals to scrutiny and potential deportation.