Electromagnetic waves share speed in vacuum; X-rays have shorter wavelengths

Steps:

• All electromagnetic waves, including microwaves and X-rays, propagate at the speed of light $c$ in vacuum, so X-rays speed is X.
• Microwave wavelengths are on the order of magnitude Y (typically centimeters to meters).
• X-ray wavelengths are much shorter, on the order of picometers to nanometers, approximated as $10^{-Y}$ relative to microwave scale.
• Thus, X-rays have speed X and wavelength order $10^{-Y}$.

Why A is correct:

• Matches the universal speed $c = X$ for EM waves in vacuum and the relative wavelength scale where X-rays are orders smaller than microwaves.

Why the others are wrong:

• B: Speed remains X, not 10X; wavelength is shorter, not Y.
• C: Speed is X, not $10^X$; wavelength is shorter, not Y.
• D: Speed is X, not 10X; wavelength scale correct but speed incorrect.

Final answer: A