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

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