Gibbs phase rule finds application, when heat transfer occurs by

Answer: Option D

Gibbs phase rule is, $$G=C-\in +2$$
Where :
$$C$$ = Number of components
$$\in$$ = Number of phases
$$G$$ = Degree of freedom
Clearly we can see Gibbs phase rule is more useful when two or more phases are involved in the given options the condensation is the only process where more than one phase is involved so, the Gibbs phase rule finds its application there.