Which type of muscle moves involuntarily without conscious thought?

Smooth muscle is the correct choice as it operates involuntarily and does not require conscious thought for its function. This type of muscle is found in various internal structures such as the walls of hollow organs, including the intestines, blood vessels, and the bladder. Its primary role is to facilitate automatic processes such as digestion and regulating blood flow, making it crucial for maintaining essential body functions without the need for conscious input.

Skeletal muscle, on the other hand, is under voluntary control, meaning it is moved intentionally and consciously by the individual. Cardiac muscle, while also involuntary, specifically refers to the heart muscle and is sometimes distinguished in discussions about muscle types but does not encompass the broad range of involuntary muscle actions that smooth muscle does. Therefore, smooth muscle is uniquely characterized by its involuntary movement, making it the correct answer.