A solid cylindrical conductor A of radius R is carrying a current 2i. Cylindrical metallic shell of radius 2R which carries a current i as shown in the figure. If P is a point at a distance r from the common axis and B_P is the magnetic induction at P, then 

• A

  ${\mathrm{B}}_{\mathrm{P}}=\frac{{\mathrm{\mu }}_{\mathrm{o}}\mathrm{I}}{2\mathrm{\pi r}}\mathrm{at}\mathrm{r}=3\mathrm{R}$

• B

  ${\mathrm{B}}_{\mathrm{P}}=\frac{{\mathrm{\mu }}_{\mathrm{o}}\mathrm{I}}{3\mathrm{\pi r}}\mathrm{at}\mathrm{r}=\raisebox{1ex}{$3\mathrm{R}$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$

• C

  ${\mathrm{B}}_{\mathrm{P}}=\frac{{\mathrm{\mu }}_{\mathrm{o}}\mathrm{I}}{\mathrm{\pi r}}\mathrm{at}\mathrm{r}=3\mathrm{R}$

• D

  ${\mathrm{B}}_{\mathrm{P}}=\frac{2{\mathrm{\mu }}_{\mathrm{o}}\mathrm{I}}{\mathrm{\pi R}}\mathrm{at}\mathrm{r}=\frac{3\mathrm{R}}{2}$