If the Magnetic Field from a Long, Straight, Current-Carrying Wire $\mathrm{B}_{0}$

If the magnetic field from a long, straight, current-carrying wire has a magnitude $\mathrm{B}_{0}$ at a distance $\mathrm{d}$ , what is the magnitude of the field at a distance $2 \mathrm{~d}$ ?

A) also $\mathrm{B}_{0}$
B) $\mathrm{B}_{0} / 2$
C) $0.693 \mathrm{~B}_{0}$
D) $\mathrm{B}_{0} / 4$
E) $0.707 \mathrm{~B}_{0}$