Pick the set of parts from ((A), (B), (C), (D) and (E)) that join together to form a complete square. A part may be turned round but its size cannot change.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B) and (C) only
Parts form a complete square only if, placed side by side, they fill the square exactly, with no gap and no overlap. (A), (B) and (C) fill a 4 × 4 square when (B) is turned through 90° anticlockwise.
Option (1) — Incorrect. (E) has as many small squares as (C) but one of them is in a different place. (A), (B) and (E) cover as many small squares as the 4 × 4 square, but they cannot be fitted into it, or into any complete square, without a gap or an overlap.
Option (2) — Incorrect. (D) has as many small squares as (B) but one of them is in a different place. Together (A), (B) and (D) cover 14½ small squares, while the 4 × 4 square has 16, so they cannot make it; they cannot be fitted into any other complete square either.
Option (4) — Incorrect. (E) has as many small squares as (C) but one of them is in a different place. Together (A), (C) and (E) cover 17½ small squares, while the 4 × 4 square has 16, so they cannot make it; they cannot be fitted into any other complete square either.