Answer:
It's only A
Explanation:
Potassium (K) is a metal and Chlorine (Cl) is a nonmetal, and ionic compounds are formed between metals and nonmetals. So KCl forms ionic bonds.
Hydrogen (H) and Chlorine (Cl) are both nonmetals, and only covalent bonds form between nonmetals. (Only exception is when its an acid, then it's ionic)
Also, the question indicated which "pair" and not "pairs" meaning that there is only one answer, and I'm more likely to go with A rather than D.
