Answer: D) Pulmonary and aortic valves.
Explanation
There are two main heartbeats from a healthy heart.
The first beat is called the S1 or the lub, and it occurs when the atrioventricular valves (comprising the mitral and tricuspid valves) close.
The second beat is called the S2 or the dub, and it occurs when the semilunar valves (comprising the aortic and pulmonary valves) close.
Listening for heart beats is an essential part of cardiac auscultation.
Darwin called the ability of an organism to survive and reproduce in its environment fitness.
Some organisms were fit to do all of these things, whereas others were not.
The anwser is chloroplast, could you check your sheet to see if you typod anything.
