Correct Answer - Option 4 : 138 ohm
Inner diameter of outer conductor, D = 1 cm
Diameter of inner conductor, d = 0.01 cm
Characteristic impedance of coaxial cable,
\({Z_0} = \frac{1}{2\pi }\sqrt {\frac{\mu }{\epsilon}} \times ln\left( {\frac{D}{d}} \right) = \frac{{138}}{{\sqrt {{\varepsilon _r}} }}\log \frac{D}{d}\)
\( \Rightarrow {Z_o} = \frac{{138}}{2}\log \frac{1}{{0.01}} = 138\;{\rm{\Omega }}\)