Final answer:
Cardiac muscle has the greatest capillary density due to its role in pumping blood continuously, requiring a constant supply of oxygen and nutrients.
Step-by-step explanation:
The type of muscle that has the greatest capillary density is cardiac muscle. Cardiac muscle cells are found only in the heart and are highly specialized to sustain continuous contractions that pump blood throughout the body. Due to the heart's need for a constant supply of oxygen and nutrients, cardiac muscle tissue is rich in capillaries, more so than skeletal muscle or smooth muscle. While all muscle types require blood supply, the cardiac muscle's role in maintaining life-sustaining circulation means it has the densest network of capillaries to ensure adequate perfusion during its never-ending activity.
In addition to its capillary density, cardiac muscle, like skeletal muscle, is striated due to the arrangement of filaments in sarcomeres, which differs from the non-striated arrangement of smooth muscle. Furthermore, skeletal muscles, which are also called voluntary muscles, can contract and relax in short, intense bursts, whereas smooth muscle sustains longer, or even near-permanent contractions, as it controls functions like the flow of blood and blood pressure, and does not have the same requirement for high capillary density.