Mobile electrons are a distinguishing characteristic of a) an ionic bond b) an electrovalent bond c) a metallic bond d) a covalent bond

option C

Explanation:

Metallic bonds exist in the atoms of metals. mobile electrons exist in metallic bonds and are referred as electron sea.This is the property that makes metals to have a high electrical conductivity.

Electrovalent and ionic bonds are formed when a metal loses an electron to a nonmetal. covalent bonds exists when electrons are shared between molecules of same elements or of different elements.

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.