What is the difference between an essential clause and a nonessential clause?
A. An essential clause is a dependent clause, and a nonessential clause is an independent clause.
B. An essential clause is an independent clause, and a nonessential clause is a dependent clause.
C. Both essential clauses and nonessential clauses are dependent clauses, but an essential clause is needed for the meaning of the sentence while a nonessential clause can be removed without changing the meaning of a sentence.
D. An essential clause begins with the pronoun which, and a nonessential clause begins with the pronoun that.