<prompt> Lymphoid tissue called Waldeyers ring is situated in:NasopharynxOropharynxBoth nasopharynx and oropharynxBase of tongue  <response>: Waldeyers ring consists of subepilhelial collection of lymphoid tissue. It comprises adenoid, tubal tonsil both in nasopharynx and palatine tonsils, lingual tonsils and granules in posterior pharyngeal wall in oropharynx. 