There are 4 shapes on a 4x4 grid. Which shape is closest to the blue 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: blue right_triangle at (3, 3)
Distance from target shape to pink right_triangle at (0, 1): 5
Distance from target shape to green rectangle at (1, 0): 5
Distance from target shape to purple square at (0, 0): 6
Closest shape is the pink right_triangle at (0, 1) with distance 5</think>

<answer>(0, 1)</answer>