Question

Identify the type of sentence. The explorers brightened the dark cave when they lit a torch from their cooking fire. simple sentence compound sentence complex sentence compound-complex

Answer 1

The answer would be complex sentence, because it consists of an individual clause (The explorers brightened the dark cave) and a dependent clause (when they lit a torch from their cooking fire). 

Answer 2

It's a complex sentence as it consists of a main clause and of a subordinate clause.