There are 4 shapes on a 7x7 grid. Which shape is closest to the red 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: red right_triangle at (3, 1)
Distance from target shape to purple trapezoid at (1, 6): 7
Distance from target shape to cyan right_triangle at (6, 6): 8
Distance from target shape to green square at (4, 2): 2
Closest shape is the green square at (4, 2) with distance 2</think>

<answer>(4, 2)</answer>