When a change in the demand for commodity A leads to a change in demand for commodity B in the same direction, demand for A & B is
Competitive demand
Complementary demand
Composite demand
Independent demand
Correct answer is B
Complementary demand occurs when the demand for a particular product leads to the demand for a related but different product. It is also known as joint demand. For instance, the demand for computer systems would lead to a corresponding demand for software because computers cannot function without software.
When there is a change in the prices of computers, it will also affect the prices of software.