This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and PNS, Subject name: ENT
Lymphoid tissue called Waldeyer's ring is situated in: 
Select and explain. 
A. Nasopharynx, B. Oropharynx, C. Both nasopharynx and oropharynx, D. Base of tongue
C: Both nasopharynx and oropharynx
Answer: C: Both nasopharynx and oropharynx 
Explanation: Waldeyer's 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).