Which color spectrum has a low frequency and long wavelength?

The visible spectrum contains light that is perceivable to the human eye and ranges from approximately 380 nm to 750 nm in wavelength. Within this spectrum, colors vary, with red being at the low frequency and long wavelength end, followed by orange, yellow, green, blue, indigo, and violet. This means that red light has the longest wavelength (about 620 to 750 nm) and lowest frequency compared to the other colors in the visible spectrum.

In contrast, the ultraviolet spectrum consists of wavelengths shorter than visible light, which means it has a higher frequency and shorter wavelengths. Similarly, the infrared spectrum, while having longer wavelengths than visible light, is not classified as being part of the visible spectrum but instead falls within the range that the human eye cannot see, appearing beyond the red end. Lastly, the X-ray spectrum has even shorter wavelengths and higher frequencies than both visible and ultraviolet light, placing it far from the low-frequency and long-wavelength characteristics described.

Therefore, focusing on the properties of each spectrum, the visible spectrum is indeed characterized by having lower frequencies and longer wavelengths, particularly at the red end, making it the correct answer.