When preparing aqueous solution of CuSO4 students A and B weighed the pentahydrate salt CuSO4x5H2O. For calculation of molarity of their solutions student A used molar mas of the pentahydrate salt while student B used the molar mass of the anhydrous salt CuSO4. Student C said it does not matter whether we use molar mass of the pentahydrate salt or of anhydrous salt. Which of these 3 students was right