Why does carbon mostly form covalent compounds?

Correct answer: Because losing or gaining four electrons is energetically difficult

Carbon has four valence electrons and needs four more to complete its outer shell. Losing four electrons would require very high energy, while gaining four would produce an unstable, highly charged ion. Carbon therefore usually completes its valence shell by sharing electrons with other atoms, forming covalent bonds. Hence option A is correct; the other choices contradict carbon’s electronic structure or bonding behaviour.