In a wire of radius 1 mm, a steady current of 2 A uniformly distributed across the cross-section of the wire is flowing. Then the magnetic field at a point 0.25 mm from the centre of the wire is

• Correct answer
  A

  $100 \mu \mathrm{~T}$
• B

  $200 \mu \mathrm{~T}$
• C

  $300 \mu \mathrm{~T}$
• D

  $400 \mu \mathrm{~T}$

Hence, the correct answer is option: 'A'.