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

<answer>(3, 1)</answer>