$A$ long solenoid has $200$ turns per $cm$ and carries a current $i$. The magnetic field at its centre is $6.28 \times 10^{-2} \ Wb/m^2$. Another long solenoid has $100$ turns per $cm$ and it carries a current $i/3$. The value of the magnetic field at its centre is:

• A
  $1.05 \times 10^{-4} \ Wb/m^2$
• B
  $1.05 \times 10^{-2} \ Wb/m^2$
• C
  $1.05 \times 10^{-5} \ Wb/m^2$
• D
  $1.05 \times 10^{-3} \ Wb/m^2$