Which of the following are likely to form a covalent bond?

Silver atoms

Argon atoms

Sodium and chlorine atoms

Carbon and chlorine atoms

The type of bond formed between two elements is predominantly dependant on the electronegativity difference that exists between the two atoms involved, the greater the difference the more polar the bond. as Carbon and Chlorine have the least electronegativity difference from the list they will form Covalent bonds.