All electromagnetic waves have in common that they can travel at the speed of light. This is true in a vacuum, where all electromagnetic waves, regardless of their wavelength or frequency, propagate at the same speed (approximately \(3 \times 10^8\) meters per second).
The other statements are incorrect:
- Electromagnetic waves do not have the same wavelengths; they can vary widely in wavelength, from radio waves to gamma rays.
- They do not travel only through matter; they can propagate through a vacuum as well.
- The statement about "nonmoving magnetic fields" is misleading; while electromagnetic waves have oscillating electric and magnetic fields, these fields are not static; they are dynamic and propagate through space.
So, the correct answer is that all electromagnetic waves can travel at the speed of light.
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