The correct answer is:
**The sum or difference of a rational and irrational number is a rational number.**
However, please note that this statement is actually incorrect as stated. The correct reasoning is that the sum of a rational number and an irrational number is always irrational. Therefore, it is often confusing, but the relevant conclusion to the closure property is that the sum of a rational and irrational does not yield a rational number. This fact, in combination with the properties of rational numbers, leads to the conclusion regarding the nature of the sum being irrational.
If you are looking for the traditional answer regarding the property in question, you could choose the third response, which aligns more closely with the conclusion that we can't predict the sum will be rational.