Which of the following is a collection of cardiac muscle fibers?

The Bundle of His, also known as the atrioventricular bundle, is a collection of cardiac muscle fibers responsible for conducting electrical impulses from the atria to the ventricles. This specialized structure is crucial for coordinating the heart's contraction rhythm, following the electrical signal initiated by the sinoatrial (SA) node. The Bundle of His is essential for maintaining a synchronized heartbeat, as it transmits impulses that cause the ventricular muscles to contract after the atria have contracted, ensuring efficient blood flow through the heart.

The other options refer to different structures in the cardiac system that do not primarily consist of a collection of cardiac muscle fibers in the same functional context. The SA node is a pacemaker comprised of specialized cells that generate electrical impulses but is not a collection of muscle fibers. The atria are chambers of the heart that contain muscle fibers but are not defined as a collection of fibers in the sense intended by the question. The great vessels, such as the aorta and pulmonary arteries, are blood vessels and do not consist of cardiac muscle fibers at all.