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

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