Sally is a middle school girl. She is in Class Six, Grade One. How old is she? She is ________ . [ ]

A. the thirteen          

B. thirteenth

C. thirty                  

D. thirteen

在防爆区域，电缆沿工艺管线敷设时，当工艺截止的密度大于空气时，电缆应在工艺管道上方。