There are 6 shapes on a 8x8 grid. Which shape is closest to the purple right_triangle in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: purple right_triangle at (0, 5)
Distance from target shape to gray rectangle at (1, 7): 3
Distance from target shape to brown rectangle at (6, 6): 7
Distance from target shape to blue right_triangle at (3, 6): 4
Distance from target shape to red rectangle at (1, 1): 5
Distance from target shape to pink trapezoid at (7, 3): 9
Closest shape is the gray rectangle at (1, 7) with distance 3</think>

<answer>(1, 7)</answer>