In a homogeneous, isotropic elastic material, the modulus of elasticity E in terms of G and K is equal to

A

$$\frac{9KG}{G + 3K}$$

B

$$\frac{9KG}{3G + K}$$

C

$$\frac{3K + G}{3G + K}$$

D

$$\frac{6KG}{K + 3G}$$