The respiratory membrane is a combination of a. atria and alveolar sacs b. respiratory bronchioles and alveolar sacs c. alveolar and capillary walls and their fused basement membranes d. respiratory bronchioles and alveolar ducts

The answer is
b. respiratory bronchioles and alveolar sacs

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.

He should put sand around the spill in order to contain it so that it won't spread