Mock Exam Morning Session: The justification for question 25 has been corrected to state: B is correct because positive “roll yield” occurs when the futures price is below the full carry price, referred to as backwardation
contango F>S if the buyer believe the future spot price will increase, he will pay a premium to buy the future. Those situation occurs when the spot prices was increasing and volatile
Backwardation F<S if the buyer believe the future spot price will decrease, he will pay a discount to buy the future, which occurs when the spot prices was decreasing and volatile.
So for this question, take the way that the price at historic lows means the price was decreasing for a while now.