24) A

If the foramen ovale does not close, the deoxygenated blood from the right atrium will mix with the oxygenated blood in the left atrium.
This will cause the aorta (which carries oxygenated blood from left ventricle to the body) to carry some deoxygenated blood.

There would be no major effect on the heartbeat so B is wrong.

The amount of blood pumped will also not drastically change. So C is wrong.

The pulmonary vein would not be affected since it comes from the lungs.

There will be little to no change in the blood pumped to the lungs.