Answer:
The answer to your question is: CO2
Explanation:
The information given is correct, Covalent bonds occur when atoms share one or more pairs of electrons, but also, covalent bonds occur with nonmetals, then,
a.NaCl This elements form an ionic bond, so this option is incorrect.
b.Cl2 Here there are two non metals but the form one single covalent bond, so this option is incorrect.
c.CO2 Carbon dioxide forms 2 double covalent bonds.
d.NH3 ammonium only forms single covalent bonds