The correct answer is B. The Declaration of Independence wasn't intended to be a formal declaration of war, because the war started a year before it was written.
The Declaration of Independence of the United States of America was a document that marked the birth and independence of the nation, signed on July 2, 1776 and made effective on the evening of July 4, 1776. In it, the Thirteen Colonies declared their independence from the British Empire by exposing the reasons that led them to this act; with this declaration the United States of America were officially born.
Then, it was a exposition of reasons rather than a declaration of war, since the war had begun a year earlier, on April 19, 1775.