Question:

<p>The sum of two irrational numbers may be rational or irrational.</p><p><strong>Example 1:</strong> $\sqrt{2} + (-\sqrt{2}) = 0$, which is rational.</p><p><strong>Example 2:</strong> $\sqrt{2} + \sqrt{3}$ is irrational.</p><p>Since the sum can be either rational or irrational, options (a) and (b) are both incomplete. Option (c) is true but too general (the sum is always real). The most precise answer is (d) None of these, as no single characterization fits all cases.</p>