This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contrast Agents, Subject name: Radiology
Following RAIU studies demonstrate 
Select and explain. 
A. Graves Disease, B. Toxic Adenoma, C. MNG, D. Lingual Thyroid
D: Lingual Thyroid
Answer: D: Lingual Thyroid 
Explanation: None