Coaxial Cable A has twice the length, twice the radius of the inner solid conductor, and twice the radius of the outer cylindrical conducting shell of coaxial Cable B$.$ What is the ratio of the inductance of Cable A to that of Cable B$?$

a$.4ln2$

b$.2ln2$

c$.2$

d$.2ln4$

e$.4ln4$

REFERENCES: $31\mathrm{.}4$ Mutual Inductance