A Friend Tells You That He Knows of a Situation

A friend tells you that he knows of a situation in which heat is passed from one body to another body with a higher temperature. He explains that he thinks the 2nd law of thermodynamics must have been violated. Is he correct?

A) No. The cooler body can give up energy to the hotter body by radioactivity or another natural process.
B) No. If the temperature difference is small enough, heat can spontaneously flow from the cooler to the hotter body.
C) Yes. Heat cannot pass from a cooler body to a hotter body.
D) No. He forgot that if external work is done on the system this is possible.