Amber is a fossilized tree resin. The resin varies in color depending upon the tree species. It becomes hard after drying. It is used for making jewellery and ornaments. It is sometimes also consider as gemstone. It is called as fossilized resin because of the fact that the resin on being liquid traps insects, plant structures, annelids and frogs. On hardening the entire trapped material get preserved as a fossil.
On the basis of the above explanation, A. Amber is the correct option.
