Which of the following facts regarding boron and silicon is not true :
(A) Boron and silicon are semiconductors.
(B) Boron and silicon form halides which are not hydrolysed.
(C) Boron and silicon react with magnesium to form magnesium boride and magnesium silicide which are decomposed by acids to give volatile borane and silane, respectively.
(D) Both boron and silicon react with alkali to form borates and silicates containing BO4 and SiO4 tetrahedral units, respectively.
