Which of the following evidence can be used to distinguish between endocardium and epicardium? A: Endocardium is covered by single-layer flat epithelium. B: Adipose tissue can be commonly seen at the endocardium. C: Subendocardial layer that contains branches of cardiac conduction system. D: Epicardium is covered by simple cuboidal epithelium.

In the following description of the heart wall structure, the WRONG option is A: The heart wall consists of endocardium, myocardium and epicardium. B: The surface of endocardium is covered by endothelium. C: Purkinje fibers are distributed in the subendocardial layer of the ventricle (心室). D: Myocardium consists mainly of smooth muscle fibers. E: Epicardium is serosa.