Which description matches cardiac muscle?

• A. Voluntary muscle attached to bones.
• B. Non-striated muscle controlling digestive tract.
• C. Smooth muscle line the airways.
• D. Involuntary muscle tissue found only in the heart.

Answer: (D)

Cardiac muscle is an involuntary muscle tissue found only in the heart. It forms the heart walls and contracts automatically through the heart’s conduction system, so it beats without conscious control. This matches the description that specifies involuntary muscle tissue located in the heart. In contrast, voluntary skeletal muscle is attached to bones, and smooth muscle—non-striated—lines organs like the digestive tract and airways, so those descriptions refer to other muscle types.