45. 下列何者非壞死性潰瘍性牙齦炎 necrotizing ulcerative gingivitis (NUG) 的特徵?(A) 牙齦乳凸上有火山口般的凹陷(Punched-out papillae and craters)(B) 過度的角質化(hyperkeratinization)(C) 特殊氣味(odor)(D) 疼痛及出血