What is true about cardiac muscle structure ?

Cardiac muscle is striated muscle that is present only in the heart

Explanation:

Cardiac muscle tissue is a specialized, organized type of tissue that only exists in the heart. It is responsible for keeping the heart pumping and blood circulating around the body. Cardiac muscle tissue, or myocardium, contains cells that expand and contract in response to electrical impulses from the nervous system.

"a.) well–developed vascular system."