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}}$ $I=5 \mathrm{~A}$
$\therefore \quad B =4 \pi \times 10^{-7} \times \frac{1000}{50 \times 10^{-2}} \times 5$ \\
$B =1.26 \times 10^{-2} \mathrm{~T}$