Answer:
Phase change from a liquid to a gas occurring at a specific temperature and pressure
Step-by-step explanation:
Boiling is a physical process in which a substance changes its state from liquid to vapor state.
In this context ,boiling point is the threshold temperature at which changes of state from liquid to vapor occurs. The boiling point also depends upon atmospheric pressure of environment as well. For the same substance, boiling point at two different pressure will differ significantly.
For example : Boiling point of water at sea level is 100 degree Celsius
while at 6,250 ft , Boiling point of water is 93.4 degree Celsius.
Based on above discussion option B Phase change from a liquid to a gas occurring at a specific temperature and pressure is the correct answer.