There are 4 shapes on a 8x8 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 (4, 6)
Distance from target shape to green square at (3, 5): 2
Distance from target shape to purple trapezoid at (1, 3): 6
Distance from target shape to yellow right_triangle at (3, 2): 5
Closest shape is the green square at (3, 5) with distance 2</think>

<answer>(3, 5)</answer>