Official solution
Let z = x + iy
given that |Re(z)| + |Im(z)| = 4
\[ \therefore \] |x| + |y| = 4
Maximum value of |z| = 4
Minimum value of |z| = perpendicular distance of line AB from (0, 0) = \[2\sqrt 2 \]
\[ \therefore \] |z| \[ \in \] \[\left[ {2\sqrt 2 ,4} \right]\]
\[ \therefore \] |z| cannot be \[\sqrt {7} \].