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