c
Both the coils have same magnetic field,

\(B_{1}=B_{2}\)

At point \(P\)

The magnetic field will be in same direction by both coils,

\(B=B_{1}+B_{2}\)

\(=B_{1}+B_{1}\)

\(=2 B_{1}\)

The magnetic field at point \(P\) is,

\(B=2\left(\frac{\mu_{0} i r^{2}}{2\left(r^{2}+n^{2}\right)^{3 / 2}}\right)\)

\(=\frac{\mu_{0} i r^{2}}{2\left(r^{2}+n^{2}\right)^{3 / 2}}\)

Substitute the values in the above equation.

\(B=\frac{\mu_{0} \times \frac{7}{2} \times 0.1^{2}}{2\left(0.1^{2}+0.05^{2}\right)^{3 / 2}}\)

\(=\frac{56 \mu_{0}}{\sqrt{5}} T\)