A square sheet of 10 cm sides is folded along its diagonal to form an isosceles right triangle, and then hypotenuses are folded successively two times to form isosceles right triangles. What is the length of each equal side after the third folding?
You have the answer. Trap Analysis is why the other three were written.
Not a worked solution repeated four times — the specific reasoning error each wrong option was built to reward, and why this one tests execution slip.
See pricing50 are analysed free — try those first.