Answer:
C. mobile electrons in the copper can shift without disrupting the solid
Step-by-step explanation:
Most of the properties of metals results from the metallic bonds between atoms of the metals. The bond forms from the attraction between the positive nuclei of all the closely packed atoms in the lattice and the electron cloud jointly formed by the atoms losing their outermost shell electrons due to their low ionizatin energy.
This is not so in ionic solids.