The magnetic flux denisty B at a distance r from a long stright rod carrying a steady current varies with r as show in the

Which of the following figure shown the magnetic flux denstiy b at a distance r from a long straight rod carrying a steady current I ?

Magnetic field at a distance r from an infinitely long straight conductor carrying a steady current varies as

Magnetic field at a distance r from an infinitely long straight conductor carrying a steady current varies as

Magnetic field at a distance r from an infinitely long straight conductor carrying steady varies as

The magnetic flux density at a point distant d from a long straight current carrying conductor is B, then its value at distance d/2 will be-