There are 3 shapes on a 4x4 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 (2, 1)
Distance from target shape to purple square at (0, 3): 4
Distance from target shape to pink rectangle at (0, 2): 3
Closest shape is the pink rectangle at (0, 2) with distance 3</think>

<answer>(0, 2)</answer>