Explanation: From, the index (depth-range) provided below the image, we can conclude that the sea level is low abnormally at the region A as it has the maximum depth below the mean sea level in the diagram i.e -30 cm.
It is clearly represented in the index that-
Region A shows a depth of about -30 cm height below the mean sea level
Region B shows a depth of about 30-40 cm above the mean sea level
Region C shows a depth of about 5-15 cm above the mean sea level
Region D shows a depth of about -10 to -20 cm below the mean sea level.
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.
