# The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 $\mu$T. What will be its value at the centre of the loop ?
( A ) 250 $\mu T$
( B ) 125 $\mu T$
( C ) 75 $\mu T$
( D ) 150 $\mu T$