A3. Which of the following expressions has an integer value?
(A) $(\sqrt{2}-1)^{2}$
(B) $(\sqrt{2}-1)(2 \sqrt{2}+1)$
(C) $(\sqrt{2}-1)(\sqrt{2}+1)$
(D) $\left(\sqrt{\frac{1}{2}}\right)^{2}$
(E) $(\sqrt[3]{2})^{2}$
A3. When simplifying the expressions, we get only in (C) the value 1, which is the only integer solution.