In comparing the phase diagram for water with that of a solution of sugar in water, all of the following decrease except

a) the vapor pressure
b) the boiling point
c) the freezing point
d) the triple point

2 answers

The way the problem is worded I don't know if we are taking H2O as the normal and saying the sugar solution will have those effects OR if we are taking sugar solution as normal as saying water will have those properties.
If we say we have water and compare that with sugar solution, the sugar solution will have a lower freezing point, a higher boiling point, and a lower vapor pressure. You can take that information and answer the question.
freezing point