Using the Mohs scale of hardness, the mineral has a hardness greater than 6.5 (Steel nail) but less than 8.5 (Drill bit). The corundum has a hardness of 9.0, which means it cannot be scratched by a drill bit, but all the other choices have a hardness scale less than 6.5 but the mineral was not scratched by the nail. So the best answer would be B.
