Step 1: Observe the given piece.
The given jigsaw piece has multiple inward and outward steps along one side, while the opposite side is straight. To form a rectangle, the missing piece must perfectly complement these indentations and protrusions.
Step 2: Identify required properties of the missing piece.
The missing piece must have an exact inverse pattern of the stepped edges of the given piece so that, after rotation or flipping, all irregular edges cancel out and the outer boundary becomes a perfect rectangle.
Step 3: Check option (A).
Option (A), when rotated and aligned with the given piece, exactly fills all the gaps created by the protrusions and indentations of the given piece. Together, they form straight outer edges on all sides, producing a rectangle.
Step 4: Eliminate other options.
Options (B), (C), and (D) do not match the step pattern correctly. Even after rotation or flipping, they either leave gaps or create overlapping protrusions, preventing the formation of a rectangular shape.
Step 5: Conclusion.
Only option (A) can combine with the given piece to form a rectangle.
Final Answer: (A)

