The correct option is D It contains water of crystallization
Anhydrous CuSO4 is white in colour due to the absence of water molecules. When we make the solution of CuSO4 water molecules will attach to CuSO4molecule making CuSO4.Two of the orbitals interact with the water molecules and raise in energy. The energy difference is equivalent of the wavelength of blue light.
The blue colour of the CuSO4 is because of Cu(II), which means it had lost two electrons; it gives the copper a 2+ charge.
Due to the arrangement of d-orbitals, there is a splitting effect. There are 5 d orbitals that can interact with other orbitals. Two of the orbitals interact with the water molecules and raise in energy. The energy difference is equivalent of the wavelength of blue light. When the copper absorbs photons, it releases energy from the upper-level energy orbitals back to the lower orbitals, giving blue light.