Mosaics are
a.
images made with glass that has been colored by metallic salts are pieced together like a collage, and are joined by leading.
b.
images made by arranging colored pieces on a flat surface, which are held using leading.
c.
artwork created by arranging cut out or torn material pasted onto a surface. means "to glue" in french.
d.
images made by arranging stones or tiles that are then embedded with a filler to connect the colored pieces.

d. images made by arranging stones or tiles that are then embedded with a filler to connect the colored pieces.

Explanation:

    Mosaic is an artistic expression in which the author, in this case the artist, organizes small colored pieces and glues them on a surface, forming images. The pieces to be used in a mosaic can be small stone fragments, such as marble, granite, pieces of glass, pebbles, semiprecious stones and other materials, on any surface, whether fixed or transportable. The term mosaic comes from “mosaicon” which means muse. This art form has existed for millennia, since from the East the Sumerians, around seven thousand years ago, already lined pilasters with cones of colored clay and fixed in mass, forming a geometric decoration. The Greeks and Romans also used the mosaic technique at the height of their cultures to decorate the floors and walls of buildings.