Which one of the following is the correct statement?

$\text{B}{\left(\text{OEt}\right)}_{\text{3}}$  imparts green colour to the burner flame.k
A) It is a weak monobasic Lewis acid, soluble in water and in aqueous solution the boron atom completes its octet by accepting OH- from water molecules.
$B{\left(OH\right)}_3+2H_{2}O\to {\left[B{\left(OH\right)}_4\right]}^{-}+H_3{O}^{+}$

B) Only ${\text{Tl}}^{\text{3+}}$acts as an Oxidsing agent on account of inert pair effect. 

C)  In the solid state, the $\text{B}{\left(\text{OH}\right)}_{\text{3}}$ units are hydrogen bonded together into two dimensional sheets with almost hexagonal symmetry.