Based on lattice energy and other considerations which one of the following alkali metal chlorides is expected to have the highest melting point?

Melting point depends on lattice energy and ionic character:$\text{LiCl}$: Although it has the highest lattice energy (due to small size of ${\text{Li}}^{+}$), it has significant covalent character (Fajans' rule) which lowers its melting point.$\text{NaCl}$: It is primarily ionic and has a very high lattice energy.As we move from $\text{NaCl}$ to $\text{RbCl}$, the lattice energy decreases because the size of the cation increases, leading to a decrease in melting point.Thus, $\text{NaCl}$ has the highest melting point among the listed halides.