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

<answer>(2, 1)</answer>