There are 4 shapes on a 4x4 grid. Which shape is closest to the gray 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: gray rectangle at (2, 2)
Distance from target shape to green right_triangle at (1, 3): 2
Distance from target shape to orange square at (3, 1): 2
Distance from target shape to pink square at (2, 1): 1
Closest shape is the pink square at (2, 1) with distance 1</think>

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