There are 4 shapes on a 9x9 grid. Which shape is closest to the purple square in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: purple square at (5, 4)
Distance from target shape to red rectangle at (5, 5): 1
Distance from target shape to orange right_triangle at (1, 4): 4
Distance from target shape to green right_triangle at (0, 8): 9
Closest shape is the red rectangle at (5, 5) with distance 1</think>

<answer>(5, 5)</answer>