Which of the following substances has covalent bonding?

In, sodium chloride (NaCl), there is an ionic bond is formed between Na⁺ and Cl⁻ions. Neon is an inert gas so that it is stable of its monatomic form of solid. Copper (Cu) metal is transition metal and “d subshell is completely filled with electrons”. Thus, it can form ionic bonding in most cases. 

Germanium belongs to p-block and forms 4 covalent bonds with neighboring atoms.