There are 5 shapes on a 9x9 grid. Which shape is closest to the pink 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: pink right_triangle at (1, 3)
Distance from target shape to cyan rectangle at (8, 6): 10
Distance from target shape to green right_triangle at (3, 3): 2
Distance from target shape to blue square at (8, 5): 9
Distance from target shape to purple right_triangle at (6, 6): 8
Closest shape is the green right_triangle at (3, 3) with distance 2</think>

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