Select a figure from the given four alternatives which fits exactly into the following figure to form a complete square.

The correct answer is Option (1) → 

Look at the top edge of the given figure. It has a stepped pattern: a small horizontal segment, a vertical rise, and another horizontal segment. To form a complete square, the missing piece must have the exact opposite (inverse) shape to fill these gaps.

Why Option 1 is correct:

• It has a deep rectangular "slot" on the left that will accommodate the "bump" on the main figure.

• It has a diagonal/stepped rise on the right that matches the empty space in the main figure's upper-right corner.

• When we place Option 1 directly on top of the main figure, the lines align to form a perfect four-sided square.