In the Context of Filing a Lawsuit, a Complaint

In the context of filing a lawsuit, a complaint:

A) must contain sufficient facts to show that the plaintiff is entitled to some legal relief.
B) is a rule of law enabling the defendant to win even if all of the plaintiff's allegations are true.
C) was created to help deal with the increasing congestion of cases in most civil courts.
D) is a procedural device that is designed to narrow down issues to be proved at trial.