What type of muscle is primarily involved in involuntary movements?

The correct choice pertains to cardiac muscle, which is indeed responsible for involuntary movements. Cardiac muscle is a specialized form of striated muscle found only in the heart. It operates automatically, contracting rhythmically and continuously without conscious effort, which is essential for maintaining the heart's function of pumping blood throughout the body. This involuntary control is critical for life, as the heart must maintain its rhythm and beat regardless of an individual's conscious actions.

In contrast, skeletal muscle is associated with voluntary movements and is under conscious control, enabling activities like walking, running, and lifting. Voluntary muscle encompasses skeletal muscle, indicating that it is primarily under conscious control, while striated muscle could refer to both skeletal and cardiac muscle. Thus, the unique nature of cardiac muscle, being both striated yet involuntary and essential for survival, solidifies its role in involuntary bodily functions.