This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'A patient presents with headache, intermittent claudication and dizziness. Which of the following may be the underlying cause- \nSelect and explain. \nA. Tetralogy of Fallot, B. Coarctation of aoa, C. Patent ductus aeriosus, D. Atrial septal defect', 'role': 'user'}, {'content': "Answer: B \nExplanation: Most children and young adults with isolated, discrete coarctation are asymptomatic. Headache, epistaxis, cold extremities, and claudication with exercise may occur,hea murmur or hypeension in the upper extremities and absence, marked diminution, or delayed pulsations in the femoral aeries are detected on physical examination. The upper extremities and thorax may be more developed than the lower extremities. (Harrison's Principles of internal medicine, 18 th edition, page 1925 ) ASD are usually asymptomatic in early life, although there may be some physical underdevelopment and an increased tendency for respiratory infections; Cardiorespiratory symptoms occur in many older patients. Beyond the fouh decade, a significant number of patients develop atrial arrhythmias, pulmonary aerial hypeension, bidirectional and then right-to-left shunting of blood, and right hea failure. (Harrison's Principles of internal medicine, 18 th edition, page 1921 )", 'role': 'assistant'}]