There are 6 shapes on a 4x4 grid. Which shape is closest to the pink 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: pink right_triangle at (1, 1)
Distance from target shape to purple trapezoid at (1, 3): 2
Distance from target shape to orange trapezoid at (0, 3): 3
Distance from target shape to green square at (3, 0): 3
Distance from target shape to brown right_triangle at (0, 2): 2
Distance from target shape to yellow trapezoid at (3, 1): 2
Closest shape is the purple trapezoid at (1, 3) with distance 2</think>

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