There are 4 shapes on a 6x6 grid. Which shape is closest to the yellow square in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: yellow square at (4, 1)
Distance from target shape to red right_triangle at (4, 5): 4
Distance from target shape to blue rectangle at (0, 5): 8
Distance from target shape to gray right_triangle at (0, 0): 5
Closest shape is the red right_triangle at (4, 5) with distance 4</think>

<answer>(4, 5)</answer>