In a fitting-parts problem, what does it mean if an answer choice has a leftover gap after the pieces are placed?

In a fitting-parts (puzzle) problem, the correct answer assembles all the given pieces into a complete figure with no leftover gaps and no overlaps — like a finished jigsaw puzzle. If an answer choice leaves a gap (empty space that should be filled) after placing the pieces, that answer is incorrect, because a proper assembly leaves no holes. Likewise, pieces should not overlap. A gap usually signals that a piece is the wrong shape or in the wrong place. Checking for complete, gap-free, non-overlapping assembly is a key way to identify the correct answer and eliminate distractors.