There are 4 shapes on a 8x8 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, 3)
Distance from target shape to blue square at (7, 0): 7
Distance from target shape to pink right_triangle at (4, 2): 2
Distance from target shape to red right_triangle at (1, 6): 5
Closest shape is the pink right_triangle at (4, 2) with distance 2</think>

<answer>(4, 2)</answer>