Find the correct statement/statements.

(A) Goods which are consumed together are called complementary goods.

(B) The market demand curve can be derived as a vertical summation of the individual demand curves.

(C) Price elasticity of demand is a measure of the responsiveness of the demand for a good to changes in its price.

(D) If the Consumer’s prefnref cbapge in favor ofa good the demapd curve for such od shifts leftward

Choose the correct answer from the options given below:

The correct answer is (A) and (C) only.

Let us analyze each statement step-by-step to understand why this option is correct:

Statement (A): "Goods which are consumed together are called complementary goods."
This statement is correct. Complementary goods are products that are typically used or consumed in conjunction with one another. A change in the price of one good directly influences the demand for its complement. Classic examples include tea and sugar, or cars and petrol. If you consume more of one, you naturally consume more of the other.

Statement (B): "The market demand curve can be derived as a vertical summation of the individual demand curves."
This statement is incorrect. The market demand curve is derived by the horizontal summation (not vertical summation) of all individual demand curves in the market. This means that at each price level, we add up the quantities demanded by all individual consumers to find the total market quantity demanded.

Statement (C): "Price elasticity of demand is a measure of the responsiveness of the demand for a good to changes in its price."
This statement is correct. By definition, the price elasticity of demand ($E_d$) measures how sensitive the quantity demanded of a good is to a change in its price. Mathematically, it is expressed as the percentage change in quantity demanded divided by the percentage change in price:

$E_d=\frac{\%\text{ Change in Quantity Demanded}}{\%\text{ Change in Price}}$

Statement (D): "If the Consumer’s preference changes in favor of a good, the demand curve for such good shifts leftward."
This statement is incorrect. If consumer preferences change in favor of a good, it means the good has become more desirable. Consequently, consumers will want to purchase more of the good at every price level, leading to an increase in demand. An increase in demand is represented by a rightward shift of the demand curve, not a leftward shift.

Therefore, only statements (A) and (C) are correct.