The magnetic field near a current-carrying conductor is given by

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:

$A$ straight section $PQ$ of a circuit lies along the $X$-axis from $x = -\frac{a}{2}$ to $x = \frac{a}{2}$ and carries a steady current $i$. The magnetic field due to the section $PQ$ at a point $x = a$ on the $X$-axis will be:

What is the magnetic field at point $P$ in the given figure?

$A$ 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:

Two infinitely long thin wires are placed at $(1 \text{ cm}, 0 \text{ cm})$ and $(2 \text{ cm}, 0 \text{ cm})$ as shown in the figure. The same current $i$ flows in both the wires in the same direction,into the page. Let the magnetic field at the origin due to these wires be $\vec{B}$. If $B_0$ is the magnitude of the magnetic field if only the wire at $(1 \text{ cm}, 0 \text{ cm})$ was present,then the value of $B / B_0$ is