(A) :When CuSO4 is dissolved in water, the solution is warmed up.
(R) :Hydration energy of CuSO4 is higher than its lattice energy.

We know, when CuSO₄ is dissolved in water the lattice energy decreases since molecules break and bind, increasing the solubility. The hydration energy for the reaction is generally exothermic whilst the lattice energy is endothermic, and available literature suggests that exothermic reaction heat is greater than endothermic reaction heat.
Hence, correct option is: (A) Both (A) and (R) are true and (R) is correct explanation of (A)