The graph showing the variation of the magnetic field strength (B) with distance (n) from a long current carrying conductor is

Explanation

The magnetic field strength (B) at the distance (r) from a long current carrying conductor is given by
`B = (mu_0)/(2 pi) (l)/(r)`
For given current, Br = constant
i.e., as r increase, magnetic field B decrease. So, option (C) is correct.