Which of the following statements is not true ?

Question

$\begin {array} {1 1} (A)\;\text{Boron is a nonmetal while all other elements of Group 13 are metal }\\ (B)\;\text{ Boron trichloride acts as a Lewis acid} \\ (C)\;\text{Boron does not form the hydrated $B^{3+}$ ion} \\ (D)\;\text{ The stability of the +1 oxidation state decreases down the group whereas that of +3 increases } \end {array}$