**The Visible Spectrum and Wavelengths**

The visible spectrum refers to the range of electromagnetic radiation that is visible to the human eye. It includes colors ranging from red to violet. Each color corresponds to a specific wavelength of light. Wavelength is the distance between two consecutive peaks or troughs of a wave.

**Determining the Color with the Greatest Wavelength**

To determine which color has the greatest wavelength among the options given, we need to understand the arrangement of colors in the visible spectrum. The visible spectrum can be divided into the following colors, in order of increasing wavelength:

1. Violet
2. Indigo
3. Blue
4. Green
5. Yellow
6. Orange
7. Red

Among the given options, the color with the greatest wavelength is red.

**Explanation**

1. Violet: Violet light has the shortest wavelength in the visible spectrum. It has a higher frequency and energy compared to other colors.
2. Indigo: Indigo light has a slightly longer wavelength than violet light but is still shorter than the other colors in the visible spectrum.
3. Blue: Blue light has a slightly longer wavelength than indigo light.
4. Green: Green light has a longer wavelength than blue light.
5. Yellow: Yellow light has a longer wavelength than green light.
6. Orange: Orange light has a longer wavelength than yellow light.
7. Red: Red light has the longest wavelength among the visible spectrum colors.

Therefore, among the given options, red has the greatest wavelength.

**Conclusion**

In the visible spectrum, red light has the longest wavelength among the colors listed. It has the lowest frequency and energy compared to other colors in the spectrum.