There are 4 shapes on a 9x9 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 (5, 5)
Distance from target shape to orange right_triangle at (6, 1): 5
Distance from target shape to brown trapezoid at (2, 3): 5
Distance from target shape to gray square at (2, 8): 6
Closest shape is the orange right_triangle at (6, 1) with distance 5</think>

<answer>(6, 1)</answer>