A 42-year-old male from Tamil Nadu presents with a 3-month history of unilateral epistaxis and right-sided nasal obstruction. On examination, he has a right cervical lymph node (2 cm, firm, non-tender) and mild serous otitis media on audiometry. Nasal endoscopy reveals a friable, bleeding mass in the nasopharynx. Biopsy confirms undifferentiated carcinoma. What is the most likely histological type and its strongest aetiological association?