Which of the following nucleus in brain is common to IX, X & XI cranial nerves?

Nucleus ambiguus consists of large motor neurons and is situated deep within the reticular formation. The emerging nerve fibers join the glossopharyngeal, vagus and cranial pa of the accessory nerve and are distributed to voluntary skeletal muscle. The neurons in the nucleus ambiguus innervate the ipsilateral laryngeal, pharyngeal, and tongue muscles involved in breathing and in maintaining the patency of the upper airway. Ref: Clinical Neuroanatomy By Richard S. Snell, 2010, Page 204.