Which one of the following formula will be used for computing the price elasticity of demand?

A. $$\frac{{\% {\text{ Change in quantity demanded}}}}{{\% {\text{ Change in price}}}}$$

B. $$\frac{{\% {\text{ Change in price}}}}{{{\text{Cost}}}} \times 100$$

C. $$\frac{{{\text{Change in quantity demanded}}}}{{{\text{Supply}}}} \times 100$$

D. $$\frac{{{\text{National income}}}}{{{\text{Cost}}}} \times 100$$

Answer: Option A