Which of the Following Expressions Can Be Used to Compute $\frac{Q_{1}-Q_{1}}{\left(Q+Q_{2}\right) / 2} * \frac{P_{1}+P_{2}}{\left(P_{2}-P_{1}\right) / 2}$

Which of the following expressions can be used to compute the price elasticity of demand?

A) Price elasticity of demand = $\frac{Q_{1}-Q_{1}}{\left(Q+Q_{2}\right) / 2} * \frac{P_{1}+P_{2}}{\left(P_{2}-P_{1}\right) / 2}$

B) Price elasticity of demand = $\frac{\left(Q+Q_{2}\right) / 2}{\left(Q_{1}-Q_{2}\right) / 2} * \frac{\left(P_{2}-P_{1}\right) / 2}{\left(P_{2}+P_{1}\right) / 2}$

C) Price elasticity of demand = $\frac{Q_{2}-Q_{1}}{Q_{1}+Q_{2}} * \frac{P_{1}+P_{2}}{P_{2}-P_{1}}$

D) Price elasticity of demand = $\frac{Q_{2}-Q_{1}}{Q_{1}+Q_{2}} * \frac{P_{2}-P_{1}}{P_{1}+P_{2}}$