The correct answer is option 3, Intestine. The muscles of the intestine are smooth muscles, which are involuntary muscles that contract slowly but can remain contracted for a longer period of time.

Option 1, Face: The muscles in the face are skeletal muscles, which are voluntary muscles that contract quickly but cannot remain contracted for a long time.

Option 2, Arms: The muscles in the arms are skeletal muscles, which contract quickly and can also be held in a contracted state for a longer time if desired.

Option 4, Legs: The muscles in the legs are skeletal muscles, which contract quickly and can be held in a contracted state for a longer time if necessary.

In summary, the muscles of the intestine are unique in their ability to contract slowly but maintain their contraction for a longer period of time.