This case study focuses on two important herbivores in the Serengeti: buffalo and wildebeest. Their populations are strongly affected by certain bottom-up factors. Which of the following is a bottom-up factor that could impact the population sizes of these herbivores? a. predators, such as lions b. parasites c. rainfall d. earthquakes
also explain please

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.