There are 3 shapes on a 7x7 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 (2, 6)
Distance from target shape to purple right_triangle at (3, 2): 5
Distance from target shape to red right_triangle at (3, 4): 3
Closest shape is the red right_triangle at (3, 4) with distance 3</think>

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