There are 5 shapes on a 10x10 grid. Which shape is closest to the red square in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: red square at (8, 1)
Distance from target shape to green trapezoid at (4, 0): 5
Distance from target shape to pink rectangle at (8, 3): 2
Distance from target shape to purple trapezoid at (6, 7): 8
Distance from target shape to brown rectangle at (1, 0): 8
Closest shape is the pink rectangle at (8, 3) with distance 2</think>

<answer>(8, 3)</answer>