The correct answer is option 4, 1 nm. X-rays are a type of electromagnetic radiation that has a very short wavelength, ranging from about 0.01 to 10 nm. Option 1, 500 nm, corresponds to the wavelength of visible light, which is much longer than X-rays. Option 2, 5000 nm, is in the infrared region of the electromagnetic spectrum, which also has longer wavelengths than X-rays. Option 3, 100 nm, is still shorter than visible light but is still longer than X-rays. Option 4, 1 nm, is the closest to the wavelength range of X-rays. X-rays have extremely short wavelengths, and they are commonly used in medical imaging and industrial applications due to their ability to penetrate matter. It is important to note that X-ray wavelengths can vary depending on the source, so the given wavelength range is not fixed for all X-rays.