For a linear elastic and isotropic material, the correct relationship among Young’s modulus of elasticity $(E)$, Poisson’s ratio $(\nu),$ and shear modulus $(G)$ is

1. $G= \frac{E}{2(1+\nu)}$
2. $G= \frac{E}{(1+2\nu)}$
3. $E= \frac{G}{2(1+\nu)}$
4. $E= \frac{G}{(1+2\nu)}$