The following sequence of reactions is used to convert borax into boron (B).
`Na_(2)underset("Borax")([B_(4)O_(5)(OH)_(4)]).8H_(2)O overset(x)toH_(3)BO_(3)overset(Delta)toB_(2)O_(3) overset(Y)to underset("Boron")(B)`
Reagents X and Y are respectively
A. Acid, Al
B. Base, C
C. Base, Fe
D. Acid, Mg