The correct answer for this would be option B. Based on the given sentence above, the highlighted part of the sentence which is "<span>who had been to the mansion before," is called an appositive phrase. This is considered as an appositive phrase because it renames or describes the noun next to it. Hope this helps.</span>
The sentence is drawing a parallel between the two parties' reasons for going to war. Each of them is associated with a verb: one with "survive," the other with "perish." They are the two antonyms.
Antonyms are words which have opposite meanings. <em>Survive </em>means to contine living, and <em>perish </em>means to stop living.
What Lincoln meant by using this antonym-based parallelism is that the Confederacy fought to end the exisiting nation (meaning, to secede from the North and create a new nation), while the Union fought to keep the nation alive by preventing it from splitting.
The answer is, "Subordinate clause."
A subordinate clause is also known as a dependent clause, which is the opposite of an independent clause. An independent clause is a part of a sentence that can stand on its own and can still technically be a valid sentence. A dependent clause depends on the main clause to form a complete sentence.
