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

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