_______,but he still could not understand it.

A．He had been told many times

B．Having been told many times

C．Told many times

D．Although he had been told many times

患者女，50岁。牙龈增生影响咀嚼1年。检查见全口牙龈肥大增生，覆盖牙面约1/2，结节状。探诊时有出血，个别牙龈增生严重处牙齿有移位。

如果该患者进行过肾移植手术，并在1年中一直接受治疗，则最可能的诊断是（）

A.药物性牙龈增生

B.牙龈纤维瘤病

C.坏死性龈炎

D.快速进展性牙周炎

E.白血病牙龈病损