24 下列何種黏合劑(cement)之放射線不透性(radiopacity)低於牙本質(dentin)? (A)玻璃離子體(glass ionomer)黏合劑 (B)樹脂(resin)黏合劑 (C)聚羧酸鋅(zinc polycarboxylate)黏合劑 (D)磷酸鋅(zinc phosphate)黏合劑