Concept:An exceptional demand curve does not obey the normal law of demand.Explanation:The law of demand states that more is bought at a lower price and less at a higher price. An exceptional demand curve shows the opposite behaviour: quantity demanded increases even as price rises. This usually occurs when consumers expect prices to rise further in the future. Therefore, they buy more now at the current high price to avoid paying a higher price later. This makes expectation of future price increase the correct cause of an exceptional demand curve.Answer:C. expectation of future price increase