There are 5 shapes on a 8x8 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, 2)
Distance from target shape to green square at (3, 1): 1
Distance from target shape to yellow trapezoid at (7, 6): 8
Distance from target shape to gray square at (0, 6): 7
Distance from target shape to cyan square at (3, 4): 2
Closest shape is the green square at (3, 1) with distance 1</think>

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