Because cities were starting to become overcrowded and filed with pollution ________

1. The military was forced to come in and clean them up
2. Cities are using less polluting fuels in factories
3. The wealthy began moving to, and commuting from, the suburbs
4. People became healthier as their immune systems became stronger

3. The wealthy began moving to, and commuting from, the suburbs

Is that correct

Yes, that is correct. As cities become overcrowded and polluted, it often results in the wealthier residents moving to the suburbs for a better quality of life, which can help alleviate the strain on city resources and reduce pollution levels.