A woman invited her friend to her house. She made a dinner of mashed potatoes and chicken nuggets. For dessert, she cut an apple into two and offered the friend one half along with whipped cream. She then proceeded to eat her piece of the same apple with the same bowl of whipped cream. The friend died of poisoning but the host survived despite eating from the same apple. How did it happen?
She had poisoned one edge of the knife that she cut the apple with