At a distance of $10 \mathrm{~cm}$ from a long straight wire carrying current, the magnetic field is $4 \times 10^{-2}$. At the distance of $40 \mathrm{~cm}$, the magnetic field will be Tesla.
(a) $1 \times 10^{-2}$
(b) $2 \times \overline{10^{-2}}$
(c) $8 \times 10^{-2}$
(d) $16 \times 10^{-2}$