B

Step 1: Analyze the first item in Column-I, which is the magnetic flux density due to a current carrying circular coil.
The magnetic field at the center of a circular loop is maximum and diminishes as we move away. Hence, the magnetic flux density is not zero at the center but maximum. In general, it is not zero when at a certain distance from the wire.
Step 2: Examine the second item regarding the magnetic flux density at a point on a current carrying thin wire.
The magnetic field at a distance away from a thin wire is maximum at a certain point. Hence, here it can be at maximum or can be zero at points further away, based on the orientation.
Step 3: Evaluate electric field strength due to a uniformly charged ring.
As we move along the axis from the center, the electric field strength decreases continuously, hence this matches with choice [C].
Step 4: Finally, check the electric potential due to a uniformly charged ring.
The potential continuously increases as we move away from the center along the axis, so this matches with choice [D].
Therefore, using this reasoning, we conclude that:
(i) - [A] Zero
(ii) - [B] Maximum or zero at Centre
(iii) - [C] Continuously decrease as we move away from the center along the axis.
(iv) - [D] Continuously increases as we move away from the center into a definite distance along the axis.
Thus, the correct match is: (ii) - [B].