66. 最適合用於印取全口義齒初模(preliminary impression)的材料是下列何者? (A)不可逆性水凝膠 (irreversible hydrocolloid) (B)多硫化物 (polysulfide) (C)縮合式矽膠 (condensation silicone) (D)加成式矽膠 (addition silicone)