The correct option of this question will be (b).

**Solution —**

The magnetic field is given by

$B=\mu_{0} n I$

where, $\mu_{0}=4 \pi \times 10^{-7} \mathrm{~T} \mathrm{~m} \mathrm{~A}{ }^{-1}$

$ n =\frac{1000}{50 \times 10^{-2}}$ $I=5 \mathrm{~A}$

$\therefore \quad B =4 \pi \times 10^{-7} \times \frac{1000}{50 \times 10^{-2}} \times 5$ \\

$B =1.26 \times 10^{-2} \mathrm{~T}$