The correct option is A 0.05 M KNO3>0.04 M CaCl2>0.140 M Sugar>0.075 M CuSO4
We know that,
ΔTf=iKfm
So more the ΔTf value, lower the freezing point.
ΔTf ∝ i×m (Since Kf is same for all the solutions given)
i×m for,
0.05 M KNO3 = 0.05×2=0.1
0.04 M CaCl2 = 0.04×3=0.12
0.140 M Sugar = 0.140×1=0.140
0.075 M CuSO4 = 0.075×2=0.15
Since i×m is lowest for 0.05 M KNO3, it has the highest freezing point, followed by 0.04 M CaCl2 , 0.140 M sugar and the lowest freezing point will be for 0.075 M CuSO4.