**Explanation:**

**The Electromagnetic Spectrum:**
The colors we see are a result of the different wavelengths of light. Light is part of the electromagnetic spectrum, which includes all types of electromagnetic radiation. This spectrum ranges from high-frequency gamma rays to low-frequency radio waves. The visible spectrum, or the range of light that humans can see, is a small portion of this spectrum.

**Visible Light and Wavelengths:**
Visible light is the portion of the electromagnetic spectrum that our eyes can detect. It consists of different wavelengths, each corresponding to a different color. The colors of the visible spectrum, in order of increasing wavelength, are red, orange, yellow, green, blue, indigo, and violet. Red has the longest wavelength and violet has the shortest wavelength among the visible colors.

**Frequency and Wavelength:**
Frequency and wavelength are inversely related. The frequency of a wave is the number of complete wavelengths that pass a point in one second. The wavelength is the distance between two adjacent crests or troughs of a wave. As the wavelength increases, the frequency decreases.

**Color and Frequency:**
Since frequency and wavelength are inversely related, the color with the highest frequency will have the shortest wavelength. In the visible spectrum, violet has the shortest wavelength and therefore the highest frequency. Violet light has a wavelength of approximately 380-450 nanometers (nm), while red light has a wavelength of approximately 620-750 nm.

**Conclusion:**
Among the options given, violet has the highest frequency among all the colors visible to us. It has the shortest wavelength compared to red, indigo, and orange. The order of increasing wavelength and decreasing frequency in the visible spectrum is: red, orange, yellow, green, blue, indigo, and violet.