Step 1: Understanding Reflexivity.
A relation \( R \) is reflexive if for every element \( x \) in the set, the relation holds for \( xRx \). In other words, \( x - x + \sqrt{2} = \sqrt{2} \), which is irrational.
Step 2: Checking the given relation.
For the relation to be reflexive, we need to check whether \( x - x + \sqrt{2} = \sqrt{2} \) is irrational for every real number \( x \). Clearly, \( \sqrt{2} \) is irrational, so the relation is reflexive.
Step 3: Final Answer.
Since the relation is reflexive, the correct answer is option (A).