The correct answer is D) a statement of position on one issue.
A plank in a party's platform is a statement of position on one issue.
When the term "plank" is used in politics, in a party's political platform, it means that the party has reached a conclusion on any determined topic. The plank is part of the party's political platform on many issues. For instance, the party's platform on the economy, or foreign trade, or civil rights, and many others that allow the citizen to know the official posture of the party on important topics that affect the United States society.
