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': 'Single second hea sound is seen in - \nSelect and explain. \nA. TOF, B. hypeension, C. Pulmonary oedema, D. MI', 'role': 'user'}, {'content': "Answer: A \nExplanation: The four components of the tetralogy of Fallot are malaligned VSD,obstruction to RV outflow, aoic override of the VSD, and RVhyperophy due to the RV's response to aoic pressure thelarge VSD. Harrison's principle of internal medicine,20edition,pg no.1554", 'role': 'assistant'}]