Which of the following gives the value of the magnetic field according to Biot-Savart's law?

For a wire, as shown in the figure, carrying a current of $10 \,A$, find the magnetic induction field at the point $O$. (Given: $\mu_0 = 4 \pi \times 10^{-7} \,H/m$)

Given below are two statements:
Statement $(I)$: When currents vary with time,Newton's third law is valid only if momentum carried by the electromagnetic field is taken into account.
Statement $(II)$: Ampere's circuital law does not depend on Biot-Savart's law.
In the light of the above statements,choose the correct answer from the options given below:

If an electron revolves around a nucleus in a circular orbit of radius $R$ with frequency $n$,then the magnetic field produced at the centre of the nucleus will be

Two identical circular current loops of radius $R$ carrying equal currents $I$ are placed such that their axes are inclined at $45^\circ$ to each other. The distance from the center of each loop to point $P$ is $\sqrt{3}R$. The resultant magnetic field at $P$ is:

$A$ coil having $9$ turns carrying a current produces a magnetic field $B_1$ at the centre. Now,the coil is rewound into $3$ turns carrying the same current. Then,the magnetic field at the centre $B_2$ is: