Your answer would be that the sentence that is a complex sentence is the following one: Although I am tired, I will finish my homework.
Explanation:
A complex sentence has one independent clause and at least one dependent clause. The difference between an independent clause and a dependent one is that the former can stand alone as a sentence as it represents a complete thought (see 1). As you can see, 1 fails to stand alone as a sentence because it does not represent a complete idea. On the contrary, "I will finish my homework" (2) do so because it is a complete sentence: it has a subject and a predicate and does not depend on any other element.
The final draft. It's the stage where you want to fix minor details before turning it in, correcting the small stuff like grammar and spelling and punctuation.
