Boron( R = 88 Pm) Is Sometimes Added to Steel

Boron( r = 88 pm) is sometimes added to steel alloys as a hardening agent.Suppose one alloy contains approximately one B atom for every 1920 Fe atoms(r = 126 pm) .Which of the following statements regarding the boron in alloy is correct?

A) Boron probably occupies a small fraction of octahedral holes in the iron crystal lattice.
B) Boron probably occupies a small fraction of tetrahedral holes in the iron crystal lattice.
C) Boron probably occupies a small fraction of cubic holes in the iron crystal lattice.
D) Boron probably replaces a small fraction of the iron atoms in the crystal lattice.
E) The alloy is approximately 0.05% boron by mass.