A metallic sphere having inner and outer radii `a` and `b` respectively has thermal conductivity
`K=(K_(0))/r (alerleb)`
Find the thermal resistance between inner surface and outer surface.
A. `((b-a))/(4piK_(0))`
B. `((b^(2)-a^(2)))/(4piK_(a)ab)`
C. `(4 piK_(0))/((b-a))`
D. none of these