This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
[{'content': 'One of the following is a midline neck swelling \nSelect and explain. \nA. Carotid body tumor, B. Thyroglossal cyst, C. Branchial cyst, D. Cystic hygroma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Midline swelling of the neck from above downwards Ludwigs angina Enlarged submental lymph nodes Sublingual dermoid Lipoma in the submental region Thyroglossal cyst Subhyoid bursitis Goitre Lipoma & enlarged lymph nodes in the suprasternal space of burns Retrosternal goitre Thymic swelling (A dermoid cyst may occur anywhere in the midline) Ref : Bailey & Love 25/e p729', 'role': 'assistant'}]