The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are

Answer: Option B

Degree of freedom = $$C-\varnothing +2$$
For azeotropic binary mixture since number of components$$(c)=2$$
Number of phases$$(\varnothing )=2$$
Degree of freedom $$=2$$
But for azeotropic mixture since vapor composition $$=$$ liquid composition
Degree of freedom becomes $$=1$$