There are 5 shapes on a 9x9 grid. Which shape is closest to the green rectangle in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: green rectangle at (8, 6)
Distance from target shape to pink right_triangle at (1, 2): 11
Distance from target shape to yellow square at (4, 1): 9
Distance from target shape to gray rectangle at (3, 4): 7
Distance from target shape to purple right_triangle at (2, 4): 8
Closest shape is the gray rectangle at (3, 4) with distance 7</think>

<answer>(3, 4)</answer>