Skin depth at 2 GHz for a gold conductor with $$\sigma =4.55 \times 10^{7} S/m $$ is 1.5 $$\mu m$$ .Skin depth (in $$\mu m$$) at 8GHZ & 18GHZ is

A

3.00, 4.50

B

0.75, 0.50

C

0.375, 0.055

D

1.50, 1.00