Complaints that milk bottlers take enormous markups on the bottled milk sold to consumers are most likely to arise when least warranted by the actual spread between the price that bottlers pay for raw milk and the price at which they sell bottled milk. The complaints occur when the bottled-milk price rises, yet these price increases most often merely reflect the rising price of the raw milk that bottlers buy from dairy farmers. When the raw-milk price is rising, the bottlers’ markups are actually smallest proportionate to the retail price. When the raw-milk price is falling, however, the markups are greatest.
If all of the statements above are true, which one of the following must also be true on the basis of them?
(A) Consumers pay more for bottled milk when raw-milk prices are falling than when these prices are rising.
(B) Increases in dairy farmers’ cost of producing milk are generally not passed on to consumers.
(C) Milk bottlers take substantially greater markups on bottled milk when its price is low for an extended period than when it is high for an extended period.
(D) Milk bottlers generally do not respond to a decrease in raw-milk prices by straightaway proportionately lowering the price of the bottled milk they sell.
(E) Consumers tend to complain more about the price they pay for bottled milk when dairy farmers are earning their smallest profits.

Please help me know the difficulty level of this question.

Good questions I should say...what's the source rohit?

Good Question. D is the right answer