Which of the following facts regarding boron and silicon is not true ?

Question

$\begin {array} {1 1} (A)\;\text{Boron and silicons are semiconductors} \\ (B)\;\text{Boron and silicons form halides which are not hydrolysed} \\ (C)\;\text{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)\;\text{Both Boron and silicon react with alkalis to form borates and silicates containing $BO_4$ and $SiO_4$ tetrahedral units, respectively.} \end {array}$