Choose the box that is similar to the box formed from the given sheet of paper…

Concept: When a flat net of a cube is folded, two squares that are exactly one square apart in a straight row or column of the net become opposite faces of the cube — and opposite faces can never sit next to (adjacent to) each other on the folded box.

Application: Apply this rule to sheet (X):

1. The top row of the net has three squares in a straight line: blank, circle, blank. The two end (blank) squares become opposite faces of each other, with the circle face adjacent to both.

2. The bottom row also has three squares in a straight line: blank, square, black. The two end squares (blank and black) become opposite faces of each other, with the square face adjacent to both.

3. That leaves only the circle face and the square face unpaired — by elimination, the circle face and the square face must be opposite each other.

4. So on the folded cube, the circle face and the square face can never appear next to (adjacent to) each other — only on opposite sides of the box.

Cross-check: Test each option cube against this rule:

• cube (1) — the square face and the circle face are shown on two adjacent faces (touching each other), which the opposite-pair rule forbids, so cube (1) cannot be formed.

• cube (2) — the circle face and the square face are again shown on two adjacent faces, so cube (2) cannot be formed either.

• cube (3) — the square face is shown with two blank faces beside it and no circle face in sight, which fits the rule, so cube (3) can be formed.

• cube (4) — the circle face is shown with a blank face and the black face beside it and no square face in sight, which also fits the rule, so cube (4) can be formed.

Result: Only cubes (3) and (4) can be formed from sheet (X); cubes (1) and (2) are ruled out because they place the circle and square faces next to each other. Hence, only 3 and 4 only is correct.