What is the purpose of the caption in a legal document?

The correct answer emphasizes the role of the caption in establishing the document's authority. In legal documents, the caption serves as an introductory heading that identifies essential elements such as the title of the case, the court in which the matter is being heard, and the names of the parties involved. This section is crucial as it provides the framework for the document being submitted and establishes its formal standing within the legal context.

While other options may touch on related aspects, they do not accurately define the specific function of a caption. For instance, summarizing the court's ruling would typically be found in the body of the document rather than in the caption. Additionally, while the caption does reveal the parties involved, this is just one part of its broader purpose of signaling the authority and jurisdiction of the document. Outlining the subject matter of the case is similarly important but falls outside the primary function of the caption, which is to set up the context and legal stature of the document being presented.