D. May not be
I have been asked this question at a job interview.
Origin of the question is p-Block Elements in section p-Block Elements of Chemistry – Class 11
The best explanation: Boron does not occur in a free state, it occurs in the form of some compounds like borax, Kernite, orthoboric acid. Elemental Boron can be obtained through many methods like the reduction of boric for oxide with highly electropositive metals or by the reaction of Boron halides with hydrogen.