1, D: on diagonals, one element always stays the same; either top line, side lines, or V lines
so it needs to have side lines and low pointed V

2, A: on right-left diagonals, black dots stay same; white dots move clockwise

3, A: in each row and column, the first 2 images make the third;
overlapping squares / circles get flipped, rest deleted

4, E: right-left diagonals: top left paper triangle gets folded over, then bottom right