The graph illustrates pressure changes in various parts of the heart during a mammalian cardiac cycle. W, X, Y and Z show the times when a valve opens or shuts. Which row correctly names W, X, Y and Z?
- AW: atrioventricular valve opens; X: atrioventricular valve closes; Y: semilunar valve opens; Z: semilunar valve closes
- BW: atrioventricular valve closes; X: semilunar valve opens; Y: semilunar valve closes; Z: atrioventricular valve opens
- CW: semilunar valve opens; X: semilunar valve closes; Y: atrioventricular valve opens; Z: atrioventricular valve closes
- DW: semilunar valve closes; X: atrioventricular valve opens; Y: atrioventricular valve closes; Z: semilunar valve opens