Which method does the CDC light trap use to attract mosquitoes?

The CDC light trap primarily uses dry ice to attract mosquitoes. Dry ice emits carbon dioxide as it sublimates, and this release of CO2 mimics the breath of potential hosts, such as humans and animals, making it a highly effective lure for mosquitoes. Mosquitoes are naturally drawn to carbon dioxide, which helps them locate their hosts when seeking a blood meal.

The other methods mentioned, while they may play a role in attracting insects in general, are not utilized by the CDC light trap. For instance, pheromones are chemicals used by various species to communicate and attract mates, but they are not the primary attractant in this context. Natural scents can attract some insects but are not specific to the CDC light trap's mechanism. Ultrasonic waves have been promoted as a repellent for some pests but lack scientific support as an effective method for attracting mosquitoes, making the use of dry ice the correct answer in this scenario.