There are 4 shapes on a 8x8 grid. Which shape is closest to the gray 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: gray right_triangle at (7, 5)
Distance from target shape to brown right_triangle at (2, 3): 7
Distance from target shape to yellow square at (0, 4): 8
Distance from target shape to purple right_triangle at (2, 0): 10
Closest shape is the brown right_triangle at (2, 3) with distance 7</think>

<answer>(2, 3)</answer>