The fractional change in the magnetic field intensity at a distance ‘r’ from centre on the axis of current carrying coil of radius ‘a’ to the magnetic field intensity at the centre of the same coil is:

Options

A. `3/2(a^2/r^2)`
B. `2/3(a^2/r^2)`
C. `2/3(r^2/a^2)`
D. `3/2(r^2/a^2)`