JAMB Physics 1999 Question 16

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?

1. A.I, II and III
2. B.I, II, III and IV
3. C.I, II and IV
4. D.II, III and IV.