Which is true on the subarachnoid space in the vertebral canal（）。
A.lies between dura matter and arachnoid
B.up to subarachnoid space in the skull by the foramen magnum
C.down the the height of the fifth sacral vertebral
D.terminal cistern is formed by the space below the second sacral vertebral
E.the fluid in it can communicate with that in the center canal of spinal cord directly
