Answer:The material that best simulates the behavior of sand, which acts like soil when at rest but behaves like a liquid when shaken during an earthquake, is B. Cornstarch.Cornstarch mixed with water forms a non-Newtonian fluid, which means it behaves like a solid under slow stress (when at rest) but behaves like a liquid when subjected to sudden force or shaking, similar to how sand behaves during an earthquake (a phenomenon known as "liquefaction").