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

<answer>(3, 2)</answer>