Selina knew the answer to this question, every child born in the wizarding world had to know this answer. People always heard the stories of Harry Potter and his evil counterpoint Lord Voldermort. Therefore, she knew that the heir of Slytherin was Lord Voldermort. The redhead rose her hand and said, "The heir of Slytherin was Tom Riddle or, erm,V-Voldermort."

And a fact? "Didn't Professor Hagrid who was an ally of Harry Potter in the Great War get expelled for the accusation of the murder?"