Question

which is a complete sentence? lichens flourish in some of the most extreme environments on earth. quinn wept during the movie, it had an emotional ending.

Explanation:

A complete sentence has a subject and a predicate and expresses a complete thought. "Lichens flourish in some of the most extreme environments on Earth" is a complete sentence with "Lichens" as the subject and "flourish in some of the most extreme environments on Earth" as the predicate. The second sentence "Quinn wept during the movie, it had an emotional ending" is a run - on sentence as it combines two independent clauses ("Quinn wept during the movie" and "it had an emotional ending") without proper punctuation or a conjunction.

Answer:

Lichens flourish in some of the most extreme environments on Earth.