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

<answer>(3, 0)</answer>