[单选题]
The heat required to change a substance fuife1gd3 75k7;cn 7ck i1zmbswn,ni 9r,2zaoryq61dv/ pkmv 075 yayi om the liquid to the vapor state is referred to1r,6oiy 7p 2ydv5yam/akz0 vq as the
A. heat of fusion.
B. heat of vaporization.
C. heat of evaporation.
D. heat of condensation.
