행렬 $A= \begin{pmatrix*}[r] 1 & -1 & 0 & 0 & 1 \\ 2 & 0 & 2 & 0 & 0 \\ 0 & 0 & 0 & 0 & 3 \\ 0 & 1 & 1 & 0 & 1 \end{pmatrix*}$ 의 계수(rank)는?

• ①$1$
• ②$2$
• ③$3$
• ④$4$
• ⑤$5$