Correct option (d) Chromium sulphate
Explanation:
Sodium chloride : NaCl
Copper chloride : Cu2Cl2
Magnesium sulphate : MgSO4
Chromium sulphate : Cr2(SO4)3
Maximum number of particles (i.e. ions) will be obtained when Cr2(SO4)3 is dissolved in water hence, 0.1 M solution of chromium sulphate will show maximum elevation in boiling point.