30.腦脊髓液循流進入上矢狀竇(superior sagittal sinus)中,需要靠下列那層構造形成顆粒突向竇中?(A)骨膜層硬膜(periosteal layer of dura)(B)腦膜層硬膜(meningeal layer of dura)(C)蛛網膜(arachnoid mater)(D)軟腦膜(pia mater)