There are 3 shapes on a 10x10 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 (5, 8)
Distance from target shape to brown right_triangle at (4, 3): 6
Distance from target shape to gray right_triangle at (8, 6): 5
Closest shape is the gray right_triangle at (8, 6) with distance 5</think>

<answer>(8, 6)</answer>