Today, some mountain ranges are rising due to tectonic plates colliding, and earthquakes are sometimes caused by tectonic plates sliding against each other. during earth's past, a. there were earthquakes, but no mountains were rising. b. mountains were rising, but there were no earthquakes. c. the tectonic plates were not moving. d. similar tectonic movements were occurring.

true is the answer : )

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.