Concept:A shift from
D0D0 to
D2D2 shows an increase in demand caused by a change in a non-price factor.
Explanation:The movement is a shift of the whole demand curve, not a movement along the same curve.
Since commodity X is a normal good, a fall in consumer income would decrease demand and shift the curve leftward.
A rise in the price of a complement would make X more expensive relative to its complement, reducing demand.
A fall in the supply of commodity X affects quantity supplied, not the demand curve.
However, a rise in the price of a substitute makes the substitute less attractive to consumers.
As a result, consumers buy more of commodity X at every price, causing the demand curve to shift rightward from
D0D0 to
D2D2.
Answer:B. Rise in the price of a substitute.
