A current of 1/(4$\pi$) ampere is flowing in a long straight conductor. The line integral of magnetic induction around a closed path enclosing the current carrying conductor is

• A

  ${10}^{-7}Wb{m}^{-1}$

• B

  $4\pi \times {10}^{-7}Wb{m}^{-1}$

• C

  $16{\pi }^2\times {10}^{-7}Wb{m}^{-1}$

• D

  zero