A 6-year-old child has purulent inflammation of the middle ear that was complicated by purulent inflammation of the mastoid cells. Trepanation (dissection) of the mastoid process became necessary. In this case, the surgeon must remember that a certain venous sinus is located close by, to avoid damaging it. Name this sinus.

• A. Transverse sinus
• B. Superior sagittal sinus
• C. Inferior sagittal sinus
• D. Sigmoid sinus
• E. Cavernous sinus