The dipole moment of a circular loop carring a current I , is m and the magnetic field at the centre of the loop is `B_(1) ` . When the dipole moment is doubled by keeping the current constant , the magnetic field at the centre of the loop is ` B_(2) ` . the ratio ` B_(1) // B_(2) ` is

Options

A. `sqrt(2) `
B. `(1)/( sqrt(2))`
C. `2`
D. `sqrt(3)`