Why is it so difficult for researchers to figure out where the aztec came from

It is difficult for researchers to find out where the Aztec came from as it entails different ethnic groups of central Mexico. Researchers prefer to say that those things that are characteristic of the Aztec culture are not really exclusive of such culture, giving way to the broader concept of Mesoamerican Culture.

answer: c  

the factory goes out of business, causing the workers to lose their jobs.

explanation:

increase in population