To find the coordinates of the point \( Y' \) after a \( 180^\circ \) counterclockwise rotation about the origin, you can use the following rule:
For any point \( (x, y) \), after a \( 180^\circ \) rotation about the origin, the new coordinates will be \( (-x, -y) \).
Starting with the coordinates of point \( Y(-2, 6) \):
- The \( x \) coordinate is \( -2 \), so after rotation it will be \( -(-2) = 2 \).
- The \( y \) coordinate is \( 6 \), so after rotation it will be \( -6 \).
Thus, the coordinates of \( Y' \) after the rotation will be \( (2, -6) \).
So, the correct answer is: A. \( Y'(2, -6) \).