Which condition on \(x\) is required for the function \(f(x)=\sqrt{x-5}\) to have real values?

Correct answer: \(x\ge 5\)

The expression under a real square root must be non-negative. Thus, \(x-5\ge 0\), which gives \(x\ge 5\). Therefore, the domain is \([5,\infty)\). Option B is incorrect because \(x=5\) is also allowed, giving \(f(5)=0\). Exam tip: For a square-root function, set the radicand greater than or equal to zero to find the domain.