Discover the best answers at Westonci.ca, where experts share their insights and knowledge with you. Connect with a community of experts ready to provide precise solutions to your questions on our user-friendly Q&A platform. Our platform provides a seamless experience for finding reliable answers from a network of experienced professionals.

Which physiologic mechanism causes the first heart sound?

a. Closing of the mitral valve
b. Filling of the ventricle
c. Closing of the aortic valve
d. Closing of the pulmonic valve