What Is the Functional Significance of Large Areas of Cardiac

What is the functional significance of large areas of cardiac muscle being electrically coupled to form a single functional syncytium?

A) Because they form a syncytium, cardiac muscles can contract on their own.
B) Because they form a syncytium, muscle cells can pass an action potential along a large area of the heart wall, stimulating contraction in each muscle fiber of the syncytium.
C) Because they form a syncytium, muscle cells cannot summate contraction to produce tetanus, and thus do not fatigue.
D) Because they form a syncytium, cardiac muscle cells can pass an action potential by way of internodal bundles contracting both atrial chambers.