Final answer:
Ionic solids have strong intermolecular forces, requiring a large amount of energy to melt them, resulting in relatively high melting points.
Step-by-step explanation:
An ionic solid is a crystalline solid composed of ions, held together by strong electrostatic attractions between oppositely charged cations and anions. This means that ionic compounds have strong intermolecular forces, which require a large amount of energy to break. Therefore, the amount of energy required to melt an ionic solid is large, leading to relatively high melting points of ionic solids. The correct answer is option A: strong; large; high.