1. The problem asks: After a 270° counterclockwise rotation about the origin, which triangle does triangle A map to? 2. Rotation rule: A 270° counterclockwise rotation about the origin transforms a point $(x,y)$ to $(y,-x)$. 3. Triangle A is in the top-left quadrant. Applying the rotation to each vertex of triangle A moves it to the top-right quadrant. 4. Since triangle B is in the top-right quadrant, triangle A maps to triangle B after the rotation. 5. Therefore, the image of triangle A after a 270° counterclockwise rotation about the origin is triangle B. **Final answer:** Triangle B