This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of orbit, Lids and lacrimal apparatus, Subject name: Ophthalmology
Thyroid eye disease is due to- 
Select and explain. 
A. Thyrotoxicosis, B. Hypothyroidism, C. Euthyroidism, D. Hashimoto's disease
A: Thyrotoxicosis
Answer: A: Thyrotoxicosis 
Explanation: *Thyroid Opthalmopathy, also called thyroid orbitopathy, is a disease of the orbit seen in Graves diseases (thyrotoxicosis), Therefore also called Graves ophthalmopathy. Ref: Kanski's Clinical Opthalmology 8th/e p.82