There are 5 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, 5)
Distance from target shape to gray trapezoid at (2, 2): 4
Distance from target shape to green trapezoid at (1, 4): 3
Distance from target shape to brown square at (0, 0): 8
Distance from target shape to purple right_triangle at (5, 0): 7
Closest shape is the green trapezoid at (1, 4) with distance 3</think>

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