Answer:
Compared with human vision, these snakes can sense electromagnetic waves that have:
3. a lower frequency and a longer wavelength.
Step-by-step explanation:
Human eyes are not able to detect the infrared region of the electromagnetic spectrum. We can experience it as heat when, for instance, we get close to a hot object. The snakes mentioned in the passage, however, have special sensory organs that can detect infrared, which means they sense waves that have a lower frequency and a longer wavelength than the ones visible to us. Let's compare infrared to what is detectable by human eyes:
Visible: wavelength: 400 nm – 700 nm; frequency: 790 THz – 430 THz.
Infrared: wavelength: 700 nm – 1 mm; frequency: 430 THz – 300 GHz.
The longer the wavelength, the lower the frequency.