2:I[5751,[],""] 4:I[8003,["138","static/chunks/138-338b445c4cbceabf.js","3","static/chunks/3-b4862a6e1de95ec0.js","628","static/chunks/app/papers/%5BpaperId%5D/%5Byear%5D/%5Bid%5D/page-257c971832fd49dc.js"],"default"] 6:I[9275,[],""] a:I[1343,[],""] b:I[101,["138","static/chunks/138-338b445c4cbceabf.js","987","static/chunks/app/papers/%5BpaperId%5D/%5Byear%5D/layout-3942c697a7972a68.js"],"default"] c:I[6324,["138","static/chunks/138-338b445c4cbceabf.js","987","static/chunks/app/papers/%5BpaperId%5D/%5Byear%5D/layout-3942c697a7972a68.js"],"default"] 13:I[4080,["185","static/chunks/app/layout-f07fbac6855a712f.js"],""] 14:I[231,["138","static/chunks/138-338b445c4cbceabf.js","986","static/chunks/986-a23d2b0476d0b49a.js","368","static/chunks/app/papers/%5BpaperId%5D/page-879e8aaf99bd7bd0.js"],""] 16:I[6130,[],""] 5:T500,

Answer: ["A","C","D"]

Key insight
All four pieces must be used with no gaps, no overlaps, and no leftover pieces. First verify that each option's total area equals the sum of the four pieces' areas, then check if the outline is achievable.

Step by step
Step 1: Count the total area of the four pieces (triangle units on the grid). Every valid option must have the same total area.
Step 2: Option A — area matches; the four pieces can be arranged (with rotation/flipping) to fill this shape. ✓
Step 3: Option B — the shape's concavities or outline require a piece arrangement that is geometrically impossible with the given pieces. ✗
Step 4: Option C — valid arrangement possible. ✓
Step 5: Option D — valid arrangement possible. ✓
Therefore the answer is A, C, and D.

Why wrong options are wrong
Option B: The shape's outline cannot be filled by any combination of the four given pieces without leaving a gap or overlap.

Remember for exam
Always start with area verification — if a shape option has a different are

Which of the options can be made using all the four pieces shown in the top row? Flipping the pieces is allowed.