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\'wave in JVP is seen in- \nSelect and explain. \nA. Will be large when atria contracts against resistance, B. Filling of ventricles, C. It is followed by "V" waves, D. in inspiration', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The a wave is due to atrial systole.some blood regurgitates into great veins when the atria contract.In addition,venous flow stops, the resultant rise in venous pressure contributes to a wave. (Ganong&;s Reviw of medical physiology,23rd edition,pg no.512)', 'role': 'assistant'}]