There are 4 shapes on a 6x6 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 (5, 2)
Distance from target shape to pink square at (5, 1): 1
Distance from target shape to purple trapezoid at (0, 1): 6
Distance from target shape to red rectangle at (3, 3): 3
Closest shape is the pink square at (5, 1) with distance 1</think>

<answer>(5, 1)</answer>