There are 6 shapes on a 8x8 grid. Which shape is closest to the green 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: green rectangle at (1, 4)
Distance from target shape to red trapezoid at (6, 2): 7
Distance from target shape to blue right_triangle at (3, 0): 6
Distance from target shape to gray right_triangle at (5, 3): 5
Distance from target shape to pink right_triangle at (1, 0): 4
Distance from target shape to purple right_triangle at (3, 4): 2
Closest shape is the purple right_triangle at (3, 4) with distance 2</think>

<answer>(3, 4)</answer>