<span>D.Oxygen will diffuse from an area of higher concentration (outside the cell) to an area of lower concentration (inside the cell). This is because cells respire constantly, as this process uses up oxygen cells will contain less oxygen than its surroundings. Oxygen moves by the process of diffusion, in diffusion a molecule will always move from a higher concentration to a lower concentration.</span>
Carbon Dioxide is the main cause, but other effectors include nitrous oxide and <span>methane.
Hope this helps!</span>
Plagues wiped out the entire crop in a large region
<span>Answer:The blood-brain
barrier (BHE)
BHE is a barrier that's highly permeability selective and protects
the central nervous system from potential dangers like viruses, bacteria and parasytes that may be circulating int he blood. <span>It is composed of endothelial cells, astrocytes, pericytes.</span></span>