When the P Waves Seem to "March Through" the QRS

Multiple Choice

When the P waves seem to "march through" the QRS complexes it indicates:

A) a complete blockage of the AV node.
B) the atria are firing at a much faster rate than the ventricles.
C) the impulses are arising from the middle of the left atrium.
D) the atria are firing chaotically at a rate of greater than 350 beats per minute.