患牙龋坏严重，有反复牙痛史和肿胀史，患牙颊侧龈黏膜可见一肉芽状瘘口。拔除患牙可见根尖粗糙不平，有污秽分泌物，根尖区牙周膜内脓肿形成，周围为炎性肉芽组织。病理诊断为（）

A.根尖周肉芽肿

B.急性根尖周炎

C.牙槽脓肿

D.根尖周囊肿

E.根尖周脓肿

As we all know, it was _____ that resulted in the terrible car accident.

A．because of her carelessness

B．her being careless

C．because she was careless

D．she was so careless