There are 4 shapes on a 6x6 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 blue square at (3, 4): 3
Distance from target shape to yellow square at (5, 0): 3
Distance from target shape to purple square at (3, 0): 1
Closest shape is the purple square at (3, 0) with distance 1</think>

<answer>(3, 0)</answer>