Final answer:
The left ventricle is the most muscular compartment of the heart.
Step-by-step explanation:
The most muscular compartment of the heart is the left ventricle.
The left ventricle is responsible for pumping oxygenated blood to the rest of the body through the systemic circulation. It is more muscular than the right ventricle because it needs to generate enough force to overcome the resistance of the entire body.