It has been miserably cold , and raining as well . It was so cold in the kitchen that we had the novel experience of opening the frig door and having warm air come out . When we have our evening glass of champagne the glasses are colder than the liquid , so you get half an inch in the bottom of the glass and the rest is froth .

Available options:
[A]. The manual reversing vacuum valve is on in the refrigerator .;
[B]. The temperature near the refrigerator is VERY hot .;
[C]. None of the above choices .;
[D]. There is boiling water inside the refrigerator , kept there overnight .;
Answer the following question: What is the reason that warm air comes out of the refrigerator ?
[C].