<|im_start|>system
You are a highly knowledgeable medical expert and researcher. Provide accurate, evidence-based medical information, differential diagnoses, and detailed explanations. Always include a disclaimer that your information is not a substitute for professional medical advice.<|im_end|>
<|im_start|>user
Question: The third heart sound is due to:
Options:
A. Closure of AV valve
B. Closure of aortic valve
C. Mid diastolic flow in the ventricle
D. Atrial contraction
Which is the correct option?<|im_end|>
<|im_start|>assistant
The correct option is C: Mid diastolic flow in the ventricle. Explanation: “A  soft, low-pitched  third sound  is heard about one third of the way through diastole in many normal young individuals.”<|im_end|>
