Final answer:
(A) CO₂ (carbon dioxide) is the substance with covalent bonds, as it is composed of non-metal atoms that share electrons.
Step-by-step explanation:
The substance that has covalent bonds among the options given is CO₂ (carbon dioxide). In covalent bonds, electrons are shared between non-metal atoms, as opposed to ionic bonds, where electrons are transferred between a metal and a non-metal, creating ions that are held together by electrostatic forces.
Since CO₂ is composed of one carbon atom and two oxygen atoms, all of which are non-metals, they share electrons, forming covalent bonds.
On the other hand, substances such as KF (potassium fluoride), NaF (sodium fluoride), and MgI₂ (magnesium iodide) involve a metal and a non-metal, indicative of the formation of ionic bonds.