3. What sedimentary rock is made up of pieces
of shells?
6. EXPLAIN: Why does sedimentary rock form
in layers?
7. EXPLAIN: Why must water evaporate or be
pressed out for sedimentary rock to form?

6. Because of how old the rocks are

Explanation:

6. Sedimentary rock forms in layers because of the order they were formed. The older rocks will form first and as time goes on, rock forms above it to create a new layer, and  so on.

it's c. (to reduce the greenhouse effect/carbon gasses)

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.