There are 3 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, 0)
Distance from target shape to gray square at (1, 4): 6
Distance from target shape to green rectangle at (5, 5): 7
Closest shape is the gray square at (1, 4) with distance 6</think>

<answer>(1, 4)</answer>