There are 5 shapes on a 6x6 grid. Which shape is closest to the green 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: green right_triangle at (3, 0)
Distance from target shape to purple rectangle at (3, 1): 1
Distance from target shape to cyan trapezoid at (0, 2): 5
Distance from target shape to brown trapezoid at (5, 2): 4
Distance from target shape to pink square at (1, 3): 5
Closest shape is the purple rectangle at (3, 1) with distance 1</think>

<answer>(3, 1)</answer>