D

Zinc phosphate cement has the highest modulus of elasticity (rigidity) among conventional dental bases/luting cements, outperforming glass-ionomer, polycarboxylate and far surpassing ZOE, making it the best choice to rigidly support a complex amalgam restoration [Craig et al., 1976, PMID 1062449; Oilo & Espevik, 1978, PMID 281671].