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

<answer>(1, 2)</answer>