Which fibers distribute the electrical impulse to the ventricles, causing them to contract?
Correct Answer: A
Rationale: The correct answer is A: Purkinje fibers. Purkinje fibers are specialized cardiac muscle fibers that distribute the electrical impulse from the AV node to the ventricles, causing them to contract. They are located in the ventricles and ensure synchronized and efficient contraction. The SA node (B) is the pacemaker of the heart, initiating the electrical impulse. The AV node (C) delays the impulse to allow for atrial contraction before ventricular contraction. The Bundle of His (D) is a pathway for the electrical impulse from the AV node to the bundle branches, which then lead to the Purkinje fibers for ventricular contraction.