The diagram illustrates the valves within the heart. When the atria are relaxed and the ventricles are contracted, which valves are open and which are closed?
- Avalves open: 3 and 4; valves closed: 1 and 2
- Bvalves open: 2 and 4; valves closed: 1 and 3
- Cvalves open: 2 and 3; valves closed: 1 and 4
- Dvalves open: 1 and 4; valves closed: 2 and 3