A compound complex sentence is a sentence that contains 2 independent clauses and an independent clause. An independent clause is one that can stand alone as a sentence, and a dependent clause cannot and wpuld be considered a fragment alone.
Sentence 1 is the compound-complex sentence because it fits the constraints above.
Independent -
Braden loves the ocean
he snorkels
Dependent -
because he is looking for different types of fish.
Sentence 2 is a run-on.
Sentence 3 is a compound sentence.
Sentence 4 is actually simple even though it seems complex.
I hope this helps!
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