There are 5 shapes on a 4x4 grid. Which shape is closest to the brown 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: brown rectangle at (3, 1)
Distance from target shape to yellow trapezoid at (3, 3): 2
Distance from target shape to pink trapezoid at (0, 1): 3
Distance from target shape to blue rectangle at (2, 1): 1
Distance from target shape to red right_triangle at (0, 3): 5
Closest shape is the blue rectangle at (2, 1) with distance 1</think>

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