The numbers $1, 2,\dots$,$9$ are arranged in a $3 \times 3$ square grid in such a way that each number occurs once and the entries along each column, each row, and each of the two diagonals add up to the same value. If the top left and the top right entries of the grid are $6$ and $2$, respectively, then the bottom middle entry is
- None of the options
- $1$
- $2$
- $4$