What type of muscle is responsible for involuntary movements?

The type of muscle responsible for involuntary movements is smooth muscle. Smooth muscle is found in the walls of hollow organs, such as the intestines, blood vessels, and the bladder. It functions automatically, without conscious control, allowing processes such as digestion and blood flow to occur without needing conscious thought.

Cardiac muscle, while also involuntary, is specialized for the heart and is unique in that it possesses characteristics of both smooth and skeletal muscle. Skeletal muscle, on the other hand, is primarily responsible for voluntary movements, enabling the body to move in a controlled manner when directed by conscious thought.

Thus, while cardiac muscle is involuntary, smooth muscle is the primary type of muscle that controls involuntary movements in the body. Therefore, the correct choice focuses specifically on the generalized category of involuntary muscle, which is smooth muscle.