Which of the following choices is a movement along the demand curve showing that a different quantity is purchased in response to a change in price?

a. income effect

b. change in quantity demanded

c. substitution effect

d. an increase in the price of a complement

B. Change in quantity demanded is a movement along the demand curve showing that a different quantity is purchased in response to a change in price.

The products in these type of change are called substitutes. Both products are competing against one another and the any changes in price of one may result to the change in demand of the other.

For example: Brand A and Brand B are both infant milk. They offer the same kind of benefit but Brand A is more demand than Brand B. If Brand A's price increase, then, its demand will decrease. Brand B's demand on the other hand will increase due to the price change of Brand A.