One MAIN idea of the article is that mountains are formed in two ways. What is another MAIN idea of the article? A Mountains can affect the weather and plants. B Some mountains have roads through them. C Mountain life is hard, especially for farmers. D Mountains are found in groups called ranges.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.