This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
The "subclan steal syndrome" occurs due to 
Select and explain. 
A. Occlusion /stenosis of the veebral aery, B. Occlusion/stenosis of the carotid aery, C. Occlusion of the subclan aery proximal to origin of veebral aery, D. Occlusion of the subclan aery distal to origin of veebral aery
C: Occlusion of the subclan aery proximal to origin of veebral aery
Answer: C: Occlusion of the subclan aery proximal to origin of veebral aery 
Explanation: *Subclan steal:when the arm is used,blood is stolen from the brain the veebral aery .this lead to veebro-basilar ischemia ,which is characterised by dizziness ,coical blindness and/or collapse. Ref Harrison20th edition pg 2456