The modulus of elasticity of concrete in N/mm$$^2$$ can be assumed as follows where $$F_{ck}$$ is the characteristic cube compressive strength of concrete in N/mm$$^2$$?

A

$$4000\sqrt{f_{ck}}$$

B

$$5000\sqrt{f_{ck}}$$

C

$$2000\sqrt{f_{ck}}$$

D

$$3000\sqrt{f_{ck}}$$