Answer: Subarachnoid
Explanation:
The space in the meninges below the arachnoid membrane and above the pia mater contains the cerebrospinal fluid. Cerebrospinal fluid is produced by choriod plexus( a cluster of capillaries) from the blood. Blood vessels traveling within the subarachnoid space deliver oxygen and nutrients to the spinal cord.
<span>A condition of the unconsciousness is an effect of the shut down of "Conscious Brain"
In that situation, Our Brain feels tired, and can't make any major decision
Hope this helps!</span>
B. All birds have feathers and hollow bones, but not all birds fly (ostrich, emu, kiwi, etc).
The answer would be the first option or oxygen energy system.
