There are 4 shapes on a 10x10 grid. Which shape is closest to the green right_triangle 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 right_triangle at (1, 9)
Distance from target shape to pink trapezoid at (7, 8): 7
Distance from target shape to brown rectangle at (3, 6): 5
Distance from target shape to blue right_triangle at (3, 5): 6
Closest shape is the brown rectangle at (3, 6) with distance 5</think>

<answer>(3, 6)</answer>