Let $z_1,z_2,z_3,z_4$ denotes the vertices of the parallelogram ABCD.
Mid point of $AC=\large\frac{z_1+z_2}{2}$
Mid point of $AC=\large\frac{z_2+z_4}{2}$
In a parallelogram diagonal intersect in the mid point
$\large\frac{z_1+z_3}{2} =\frac{z_2+z_4}{2}$
$z_1+z_3=z_2+z_4$
Hence 2 is the correct answer.