Explanation:

- Option 1: Intermenable is incorrectly spelled. The correct spelling is "Interminable," meaning endless or seemingly endless.

- Option 2: Intubate is correctly spelled. It refers to the medical procedure of inserting a tube into a patient's body, typically to assist with breathing.

- Option 3: Incredible is correctly spelled. It means something amazing or hard to believe.

- Option 4: Incredulous is correctly spelled. It describes a person's skepticism or unwillingness to believe something.