Answer: D - Both waves travel at the same speed in a vacuum.
X-ray waves and infrared waves (as well as all other electromagnetic waves) move at the same speed in a vacuum, the speed of light (c). This speed is a fundamental constant of the universe and is the maximum speed at which any information or energy can be transmitted.
Although X-ray waves and infrared waves have different wavelengths, frequencies, and energies, they both travel at the same speed in a vacuum because they are both forms of electromagnetic radiation, which propagates through space as a transverse wave of oscillating electric and magnetic fields. The speed of light is determined by the properties of free space and does not depend on the wavelength, frequency, or energy of the electromagnetic wave. Therefore, X-ray waves and infrared waves, like all other electromagnetic waves, travel at the speed of light in a vacuum.
