If the age of the middle layer of a rock sample is between 300 million years and 1 billion years, which of the following could be the age of the lowermost layer?

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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.