It can be deduced from the vapour pressure curves above that

The vapor pressure curves show the relationship between the boiling points and the vapor pressures of different liquids. The boiling point of a liquid is the temperature at which its vapor pressure is equal to atmospheric pressure. From the given vapor pressure curves, we can deduce that the liquid with the highest boiling point will have the lowest vapor pressure at a given temperature. Conversely, the liquid with the lowest boiling point will have the highest vapor pressure at a given temperature. Therefore, we can deduce that liquid I has the lowest boiling point since it has the highest vapor pressure at a given temperature. On the other hand, liquid III has the highest boiling point since it has the lowest vapor pressure at a given temperature. So, the correct answer is "liquid lll has the highest boiling point."