There are 5 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 (1, 0)
Distance from target shape to purple right_triangle at (2, 1): 2
Distance from target shape to pink trapezoid at (2, 3): 4
Distance from target shape to gray square at (1, 3): 3
Distance from target shape to cyan right_triangle at (3, 3): 5
Closest shape is the purple right_triangle at (2, 1) with distance 2</think>

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