A cylindrical conductor of radius R is carrying a constant current. The plot of the magnitude of the magnetic field B with the distance d from the center of the conductor is correctly represented by the figure: ABCD?

Correct option is C.
Step 1 - Magnetic field inside conductor
Refer Figure 1
B=µ₀2πiR²d ⇒B∝d ⇒B=kd [here k is constant]
Graph of B-d will be a straight line passing through the origin.
Step 2 - Magnetic field outside the conductor
Refer Figure 2
Outside (d>R) B=µ₀2πid ⇒B∝1/d (Hyperbolic)
Step 3 - Draw B - d graph
Refer Figure 3
Hence option (c) is correct.