There are 5 shapes on a 6x6 grid. Which shape is closest to the gray 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: gray right_triangle at (2, 0)
Distance from target shape to yellow rectangle at (3, 1): 2
Distance from target shape to green right_triangle at (2, 5): 5
Distance from target shape to cyan rectangle at (0, 0): 2
Distance from target shape to red square at (5, 4): 7
Closest shape is the yellow rectangle at (3, 1) with distance 2</think>

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