To solve this question, we need to understand the properties of rational numbers and how negation affects them.

1. A rational number is any number that can be expressed as the quotient or fraction \(\frac{p}{q}\), where \(p\) and \(q\) are integers and \(q \neq 0\).
2. The negative of a rational number is simply the negation of that number. If we have a rational number \(\frac{p}{q}\), its negative would be \(-\frac{p}{q}\). Since the negation operation just changes the sign of the number, the result \(-\frac{p}{q}\) is still a fraction of integers, where the denominator is not zero, thus maintaining its identity as a rational number.
3. Let's examine the options:
   • Surd: A surd is an irrational number that cannot be expressed as a simple fraction. Since the negative of a rational number is itself rational, this option is incorrect.
   • Zero: The negative of a non-zero rational number cannot be zero. Therefore, this option is incorrect.
   • A rational number: As shown, the negative of a rational number is itself a rational number. Thus, this is the correct option.
   • An irrational number: An irrational number cannot be expressed as a fraction of two integers. The negation of a rational number cannot become irrational, so this option is incorrect.
4. Conclusion: The negative of a non-zero rational number is indeed a rational number. Therefore, the correct answer is "a rational number."