Find a set of column vectors, $T$, such that (1) the span of $T$ is the null space of $B$, $\spn{T}=\nsp{B}$ and (2) $T$ is a linearly independent set. \begin{align*} B&= \begin{bmatrix} 2 & 1 & 1 & 1 \\ -4 & -3 & 1 & -7 \\ 1 & 1 & -1 & 3 \end{bmatrix} \end{align*}