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: Medicine
A 64 year old lady Kamla complains of severe unilateral headache on the right side and blindness for 2 days. On examination there is a thick cord like structure on the lateral side of the head. The ESR is 80 mm/hr in the first hour. The most likely diagnosis is: 
Select and explain. 
A. Temporal aeritis, B. Migraine, C. Cluster headache, D. Sinusitis
A: Temporal aeritis
Answer: A: Temporal aeritis 
Explanation: Answer is A (Temporal Aeritis): The symptom and the laboratory examination of the patients almost confirms the diagnosis of temporal aeritis. In an elderly patient who presents with headache, visual symptoms (blindness), malaise, fever, weakness with or without pain or tenderness over temporal aery (thick cord like structure) and a raised ESR, it is definitively suggestive of Temporal aeritis