How would a student justify inferring that "indigenous” means "originating in a particular region”?

Question

The word root “gen” means “earth,” and the suffix “-ous” means “someone who does something.”
The word root “gen” means “birth,” and the suffix “-ous” means “having the quality of something.”
The word root “gen” means “body,” and the suffix “-ous” means “the state or condition of something.”
The word root “gen” means “rule,” and the suffix “-ous” means “being filled up with something.”