I A liquid boils when its saturated vapour pres... - JAMB Physics 1999 Question

I. A liquid boils when its saturated vapour pressure is equal to the external pressure

II. Dissolved substances in pure water lead to increase in the boiling point.

III. When the external pressure is increased, the boiling point increases.

IV. Dissolved substances in pure water decrease the boiling point.

Which combination of the above are peculiarities of the boiling point of a liquid?