Ultraviolet radiation (with a wavelength in the range of 290–400 nanometers), visible light (400–760 nm), and infrared radiation (760–3,000 nm) are the three forms of energy that the Earth receives from the sun. Within the ultraviolet spectrum, the three sub categories are UVC (200–290 nm), UVB (290–320 nm), and UVA (320–400 nm). Most UVC rays do not reach the Earth because ozone and other gases in the upper atmosphere absorb them, but exposure to this type of radiation from germicidal lamps and mercury lamps may still be hazardous. Excessive exposure to visible light is also thought to be harmful, but it is not of extreme importance with respect to prevention of skin damage. Most skin damage is caused by UVA and UVB radiation.

Ten times more UVA than UVB reaches the Earth, but the amount of UVA needed to produce sunburn in human skin is 800–1,000 times higher than the amount of UVB needed. Nevertheless, UVA intensifies the sunburn effects of UVB through delayed erythema and aids in cancer formation. Thus, effective sunscreens and sun blocks must protect throughout both the UVB and UVA ranges.

Consider each of the answer choices separately and indicate all that apply.

Which of the following can be inferred from the passage?

A. A form of energy with a wavelength in the range of 2,000–2,500 nanometers would not be categorized as ultraviolet radiation.
B. UVB rays cannot cause cancer formation without the intensifying effects of UVA.
C. Ultraviolet radiation is not a form of infrared radiation.

Consider each of the answer choices separately and indicate all that apply.

The sentence “Nevertheless, UVA intensifies … cancer formation” serves which of the following roles?

A. It provides a factual basis for creating sunscreens and sun blocks with certain properties.
B. It undermines an argument presented earlier in the passage.
C. It suggests that, within the wavelength range of ultraviolet radiation, radiation with wavelength lower than 320 nm can exacerbate the carcinogenic properties of radiation with a wavelength higher than 320 nm.