Step 1: Understanding the structure of the heart.
The heart is composed of three primary layers: - Epicardium: The outer layer of the heart. - Endocardium: The inner lining of the heart. - Myocardium: The thick, muscular layer of the heart responsible for contraction.
Step 2: Analyzing the options.
(1) Epicardium: Incorrect, the epicardium is the outer layer, but it is not the thickest.
(2) Endocardium: Incorrect, the endocardium is the inner lining, not the thickest layer.
(3) Pericardium: Incorrect, the pericardium is the membrane surrounding the heart, not part of its structure.
(4) Myocardium: Correct — The myocardium is the thickest layer of the heart, composed of muscle tissue that enables the heart to pump blood.
Step 3: Conclusion.
The correct answer is (4) Myocardium.