The relation between modulus of elasticity (E) and modulus of rigidity (C) is given by

A. $${\text{C}} = \frac{{{\text{mE}}}}{{2\left( {{\text{m}} + 1} \right)}}$$

B. $${\text{C}} = \frac{{2\left( {{\text{m}} + 1} \right)}}{{{\text{mE}}}}$$

C. $${\text{C}} = \frac{{2{\text{mE}}}}{{\left( {{\text{m}} + 1} \right)}}$$

D. $${\text{C}} = \frac{{\left( {{\text{m}} + 1} \right)}}{{2{\text{mE}}}}$$

Answer: Option A