Verified Answer :

these drawings depict the steps to get the perpendicular line using a compas (and maybe a ruler)

remember that a line goes through 2 points so we need 2 different points to construct our perpendicular line


the first one is wrong because it doesn't constraint it to be perpendicular
it only has 1 point, 

2nd is wrong as well, has only 1 point, the center

3rd is right

4th is correct, hold a sec
how did that 2nd upper arc have same beginig pointn for compass?




3rd on is answer