This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
Which of the following cartilage has signet ring shape- 
Select and explain. 
A. Thyroid, B. Cricoid, C. Cuneiform, D. Arytenoid
B: Cricoid
Answer: B: Cricoid 
Explanation: Cricoid cartilage is the only cartilage forming a complete ring, therefore is shaped like a ring.