The length of the shadow of a vertical tower on level ground increases by 8.4 cm when the altitude of the sun changes from $$45^{\circ}$$ to $$30^{\circ}$$. What is the height of the tower (in m)?

A

$$4.2\left(\sqrt{3}+1\right)$$

B

$$8.4\left(\sqrt{3}+3\right)$$

C

$$4.2\left(\sqrt{3}-1\right)$$

D

$$4.2\left(\sqrt{3}+3\right)$$