Many scientists classify viruses as non-living. the single, most important reason why viruses are classified as non-living is that they
a) do not contain nuclei.
b) are not composed of cells.
c) are not able to reproduce.
d) do not contain nucleic acid.

for the points

six grader is what i am ssorry

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.

b. climate change will cause an increase in biodiversity of all ecosystems.

hope this