Task: Question Answering
Input (English): Background Paragraph: A paradox is a statement that, despite apparently valid reasoning from true premises, leads to an apparently-self-contradictory or logically unacceptable conclusion.[1][2] A paradox involves contradictory-yet-interrelated elements that exist simultaneously and persist over time.[3][4][5]. 
Story: In ancient Greece King Juno asked two of his court philosophers, philosopher A and philosopher B, to come up with two interesting problems. Philosopher A devised a clever paradox and presented it before the court. He called the  paradox Problem A. But philosopher B didn't come up with a paradox. He too presented a clever problem which was not a paradox - he called it problem B. 
Question: Which problem's elements would not persist over time?
Output (English): problem B.