Which of the following is a commonly used insecticide for adult mosquito control?

Deltamethrin is a commonly used insecticide for adult mosquito control due to its effectiveness and residual action. It belongs to the class of synthetic pyrethroids, which are designed to mimic natural pyrethrins derived from chrysanthemum flowers. Deltamethrin works by disrupting the nervous system of insects, leading to paralysis and death. Its stability in various environmental conditions makes it suitable for outdoor application, particularly in situations where controlling adult mosquito populations is essential, such as in public health campaigns against mosquito-borne diseases.

In contrast, the other options do not serve the same purpose or effectiveness in adult mosquito control. Chlorophyll is a pigment found in plants and does not function as an insecticide. Sodium chloride, commonly known as salt, does not have any insecticidal properties and is primarily used for various other applications, such as seasoning. Citronella oil, while known for its mosquito-repellent properties, is generally not categorized as an insecticide in the same way as Deltamethrin and is more effective as a repellent rather than a lethal agent against adult mosquitoes.