Concept:
In the electromagnetic spectrum, radiation is arranged according to wavelength or frequency.
Step 1: Check Assertion.
X-rays lie between ultraviolet rays and gamma rays in the electromagnetic spectrum.
\[
A \text{ is correct}
\]
Step 2: Check Reason.
X-rays have a broad wavelength range and are generally not represented only by wavelengths greater than \(6\ \text{\AA}\). Therefore, the reason is not correct as a general statement.
\[
R \text{ is not correct}
\]
Step 3: Final conclusion.
Assertion is correct but Reason is not correct.
\[
\therefore \text{Correct Answer is (C)}
\]