The heat required to change a substance from a liquid to a gas without experiencing a temperature change is defined as the latent heat of （）.

A.Overcoming sliding friction
B.Overcoming rolling friction
C.Overcoming fluid friction
D.Overcoming oil wedge friction

A.weight designation
B.viscosity index
C.pour point
D.thermal change value

A.fusion
B.vaporization
C.condensation
D.sublimation