There are 3 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 (4, 3)
Distance from target shape to yellow square at (5, 5): 3
Distance from target shape to cyan rectangle at (2, 0): 5
Closest shape is the yellow square at (5, 5) with distance 3</think>

<answer>(5, 5)</answer>