There are 3 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 (0, 3)
Distance from target shape to yellow trapezoid at (9, 6): 12
Distance from target shape to red right_triangle at (8, 1): 10
Closest shape is the red right_triangle at (8, 1) with distance 10</think>

<answer>(8, 1)</answer>