When a figure is rotated 90 degrees counterclockwise about the origin, the transformation of the coordinates (x, y) can be described by the mapping:
\[ (x, y) \rightarrow (-y, x) \]
This means the x-coordinate becomes the negative of the original y-coordinate, and the y-coordinate becomes the original x-coordinate.
Thus, the correct answer is Option #2: (x,y) --> (-y,x).