2017 Cayley Problem 21

The integers 1 to 6 are to be inserted into the grid shown. No two integers that differ by 1 may be in squares that share an edge. If the 1 is inserted as shown, how many different integers can be placed in the box labelled x?

\textbf{(A)}\ 1\quad \textbf{(B)}\ 3\quad \textbf{(C)}\ 5\quad \textbf{(D)}\ 0\quad \textbf{(E)}\ 2

If there are no answer choices shown, enter a numerical answer.

Full credit to this problem is given to the CEMC, you may view all Cayley contests here.