Question

choose the correct answer.
d is which layer?
endocardium myocardium
epicardium pericardium

Explanation:

The heart has three main tissue layers: the epicardium (outer), myocardium (middle, muscular), and endocardium (inner). The myocardium is the thick, muscular layer responsible for contraction. In the diagram, layer D corresponds to the myocardium as it is the muscular middle layer.

Answer:

B. myocardium