Answer: C
\((1 + \sqrt{2} + \sqrt{3})(1 - \sqrt{2} + \sqrt{3})\) \(= (1 + \sqrt{3} + \sqrt{2})(1 + \sqrt{3} - \sqrt{2})\) \(= (1 + \sqrt{3})^2 - (\sqrt{2})^2\) \(= 1 + 3 + 2\sqrt{3} - 2\) \(= 2 + 2\sqrt{3}\) \(= 2(1 + \sqrt{3})\)
\((1 + \sqrt{2} + \sqrt{3})(1 - \sqrt{2} + \sqrt{3})\) \(= (1 + \sqrt{3} + \sqrt{2})(1 + \sqrt{3} - \sqrt{2})\) \(= (1 + \sqrt{3})^2 - (\sqrt{2})^2\) \(= 1 + 3 + 2\sqrt{3} - 2\) \(= 2 + 2\sqrt{3}\) \(= 2(1 + \sqrt{3})\)