The correct answer is C. The bonds can shift because valence electrons are held loosely and move freely.
This property of metallic bonds allows the electrons, often referred to as "delocalized" or "sea of electrons," to move freely throughout the structure. This free movement facilitates the conduction of electricity, as these mobile electrons can carry charge throughout the metal. This characteristic, along with other properties such as malleability and ductility, is a direct result of the nature of metallic bonding.