The option that does not characterize X-rays is Option C: Deflected by electric and magnetic fields.

X-rays are a form of electromagnetic radiation, like light or radio waves, but they have much shorter wavelengths and higher energy. Here's a brief explanation of each option:

Option A: The radiation can ionise gases

X-rays have enough energy to remove electrons from atoms or molecules, thereby ionizing the gases. This is one of the properties that makes X-rays extremely useful in medical imaging and industrial applications, as they can penetrate materials and reveal information based on the level of ionization that occurs.

Option B: It causes ZnS to fluorescence

When X-rays strike certain materials, they can cause these materials to emit light in a process known as fluorescence. Zinc sulfide (ZnS) is one such material that fluoresces upon exposure to X-rays. This property is utilized in X-ray screens and detectors.

Option C: Deflected by electric and magnetic fields

This statement is false in the context of X-rays and is what sets them apart from charged particles. X-rays, being electromagnetic radiation, are not deflected by electric or magnetic fields. This property is contrasted with charged particles such as electrons, which can be deflected by these fields. Electromagnetic waves, including X-rays, propagate in a straight line and are unaffected by electric and magnetic fields because they carry no charge.

Option D: Have wavelengths shorter than ultraviolet rays

X-rays do indeed have wavelengths shorter than ultraviolet rays. The electromagnetic spectrum is ordered by wavelength and frequency, with X-rays situated between ultraviolet rays and gamma rays. The shorter the wavelength, the higher the energy of the electromagnetic waves. X-rays typically have wavelengths in the range of 0.01 to 10 nanometers, indicating higher energy and allowing them to penetrate many materials.