Identify the correct order.

The solubility of the chlorides of the alkali metal decreases down the group.

$\mathrm{CsCl}<\mathrm{RbCl}<\mathrm{KCl}<\mathrm{NaCl}<\mathrm{LiCl}$ (Solubility in water)

lithium cation has a large charge density. So lithium cation can distort the electron cloud of neighboring halide ions.

$\mathrm{CsCl}<\mathrm{RbCl}<\mathrm{KCl}<\mathrm{NaCl}<\mathrm{LiCl}$ (M.P.)

Also the Lettice energy order,

$\mathrm{CsCl}>\mathrm{RbCl}>\mathrm{KCl}>\mathrm{NaCl}>\mathrm{LiCl}$ (Lattice energy)

Hence, option C is correct.