Intestine is the correct answer.

The muscles of the intestine, known as smooth muscles, contract slowly but can remain contracted for a longer time compared to the muscles of other body parts.

Smooth muscles are involuntary muscles that are found in the walls of organs and structures throughout the body, including the intestines. They are responsible for various functions, such as moving food through the digestive system, regulating blood flow, and controlling the diameter of blood vessels.

Smooth muscles have a unique structure and function compared to skeletal muscles, which are responsible for voluntary movements. Here are some key points about smooth muscles in the intestines:

1. Slow contraction: Smooth muscles contract slowly compared to skeletal muscles. This gradual contraction allows for a controlled movement of substances through the intestines, such as the passage of food during digestion.

2. Sustained contraction: Once smooth muscles contract, they can remain contracted for a longer time compared to skeletal muscles. This sustained contraction is essential for maintaining the tone and function of the intestines, such as preventing the backflow of food or waste.

3. Peristalsis: The contraction and relaxation of smooth muscles in the intestines create a rhythmic wave-like movement known as peristalsis. This movement helps propel food through the digestive system and aids in the absorption of nutrients.

4. Autonomic control: Smooth muscles in the intestines are controlled by the autonomic nervous system, which regulates involuntary bodily functions. This means that the contraction and relaxation of these muscles are not under our conscious control.

In summary, the muscles of the intestine contract slowly but can remain contracted for a longer time compared to muscles in other body parts. This slow and sustained contraction is essential for the proper functioning of the digestive system and the movement of substances through the intestines.