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: Surgery
One of the following is an example of painless midline swelling - 
Select and explain. 
A. Branchial cyst, B. Thyroglossal cyst, C. Cystic hygroma, D. Carotid body tumour
B: Thyroglossal cyst
Answer: B: Thyroglossal cyst 
Explanation: None