Ans. is 'c' i.e., Glossopharyngeal Referred otalgiao As ear receives nerve supply from Vth (auriculotemporal branch), IXth (tympanic branch) and IXth (auricular branch) cranial nerves; and from C2 (lesser occipital) and C2 and C3 (greater auricular), pain may be referred from these remote areas.Via IXth cranial nerveDental: - Caries tooth, apical abscess, impacted molar, malocclusion.Oral cavity: - Benign or malignant ulcerative lesions of oral cavity or tongue.Temporomandibular joint disorders: - Bruxism, osteoarthritis, recurrent dislocation, ill-fitting denture.Sphenopalatine neuralgiaVia IXth cranial nerveOropharynx : - Acute tonsillitis, peritonsillar abscess, tonsillectomy. Benign or malignant ulcers of soft palate, tonsil and its pillars.Base of tongue: - Tuberculosis or malignancyElongated styloid process.Via Xth cranial cerve : Malignancy or ulcerative lesion of vallecula, epiglottis, larynx or laryngopharynx, oesophagus.Via C2 and C3 spinal nerves : Cervical spondylosis, injuries of cervical spine, caries spine.