Because, The SAS stands for Side Angle Side if you need two sides and then the angle needs to be between them.
The first one works because the angle is in-between the 2 sides. The second one really doesn't work very well. Because, It actually have 2 angles and it only need one. Well, The third one it doesn't work because the angle isn't between from both sides. The fourth one doesn't work at all they are only sides and no angles. Hope This helps <3!!
