Consider the matrix A=(121242363)A = \begin{pmatrix} 1 & 2 & 1 \\ 2 & 4 & 2 \\ 3 & 6 & 3 \end{pmatrix}A=123246123. Which of the following statements about AAA is true?
The row space dimension is 2.
The matrix is invertible.
The nullity is 2.
The rank is 1.