There are 6 shapes on a 5x5 grid. Which shape is closest to the green rectangle 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 rectangle at (1, 3)
Distance from target shape to cyan square at (4, 1): 5
Distance from target shape to red square at (2, 4): 2
Distance from target shape to orange square at (4, 3): 3
Distance from target shape to pink rectangle at (3, 3): 2
Distance from target shape to purple right_triangle at (0, 3): 1
Closest shape is the purple right_triangle at (0, 3) with distance 1</think>

<answer>(0, 3)</answer>