This is a Heyacrazy puzzle.
Rules of Heyacrazy:
Shade some cells of the grid.
Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected.
When the puzzle is solved, you may not be able to draw a line segment that passes through two borders, and does not pass through any shaded cells or grid vertices.
Here, the top solution is valid. The first three wrong solutions all break the third rule with the given red segments, and the other two break the two parts of the second rule in the indicated areas.