Final answer:
The epicardium is the visceral layer of serous pericardium and the outermost layer of the heart wall, not to be confused with the fibrous pericardium or the endocardium.
Step-by-step explanation:
The epicardium is the same as the d. visceral layer of serous pericardium. The epicardium is the outermost layer of the heart wall and is an integral part of the serous pericardium. This layer is made of a simple squamous epithelium called a mesothelium, reinforced with loose connective tissue.
It secretes serous fluid to reduce friction between the heart and surrounding structures during cardiac contraction. The fibrous pericardium is a separate, tougher layer that helps protect and anchor the heart. The endocardium is the innermost layer, lining the heart chambers and heart valves, and should not be confused with the epicardium.