A structural engineer is working on a project that involves constructing a bridge in a seismic-prone area. The engineer is tasked with selecting materials that can withstand earthquake forces. To ensure the structural integrity of the bridge, which of the following properties of engineering materials are essential to evaluate and can be easily determined in the field or laboratory?

(a) Elastic modulus

(b) Refractive index

(c) Sound absorption coefficient

(d) All of these.