How has the system of classifying organisms changed since linnaeus’s work?

a. levels have been taken away from the hierarchy.

b. organisms have been identified simply as plants or animals.

c. more levels have been added to the hierarchy.

d. a hierarchy has been developed.

C . More levels have been added to the hierarchy.

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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.