Which three of the four pieces below can be fitted together to form a perfect square?

To determine which three of the four pieces can fit together to form a perfect square, you would need to analyze the shapes and dimensions of each piece. Look for combinations that together create equal lengths along all sides, ensuring they can enclose a square without gaps or overlaps. Without the specific details or images of the pieces, it's impossible to provide a definitive answer. Please provide more information on the pieces for further assistance!