Final answer:
Polycrystalline materials are composed of many crystals or grains and are anisotropic, exhibiting different properties in different directions, unlike monocrystalline, isotropic, or non-crystalline materials. The option (A) is correct.
Step-by-step explanation:
Crystalline materials that are composed of more than one crystal or grain and exhibit different physical properties in different directions are known as anisotropic materials. The correct option that describes such materials is polycrystalline. Polycrystalline materials are made up of many crystals or grains, which are often randomly oriented, causing varying characteristics depending on the direction of measurement.
In contrast, monocrystalline materials are made up of a single crystal or grain, which means they exhibit uniform properties in all directions. Isotropic materials have identical properties in all directions and do not depend on the crystalline structure, whereas non-crystalline materials refer to amorphous solids without a well-defined crystalline structure. Therefore, option (A) is correct.