Consider the real vector space $V=\mathbb{R}^{4}$. For each of the following five statements, provide either a proof or a counterexample.
(a) $\operatorname{dim} V=4$.
(b) $\operatorname{span}((1,1,0,0),(0,1,1,0),(0,0,1,1))=V$.
(c) The list $((1,-1,0,0),(0,1,-1,0),(0,0,1,-1),(-1,0,0,1)$ )s linearly independent.
(d) Every list of four vectors $v_{1}, \ldots, v_{4} \in V$, such that $\operatorname{span}\left(v_{1}, \ldots, v_{4}\right)=V$, is linearly independent.
(e) Let $v_{1}$ and $v_{2}$ be two linearly independent vectors in $V$. Then, there exist vectors $u, w \in V$, such that $\left(v_{1}, v_{2}, u, w\right)$ is a basis for $V$.