The benefit of having at least a partial separation of pulmonary and systemic circulation is that

A) oxygenated and deoxygenated blood do not mix.
B) blood moving to the body tissues is at a higher pressure than it would be if it had flowed directly from the lungs to the body.
C) blood moving to the lungs is at a higher pressure than it would be if it had come directly from the body.
D) blood moving to the body tissues is at a lower pressure than it would be if it had flowed through the lungs first.
E) there are two muscular regions for pumping.