Which type of systemic pesticide is absorbed by and circulates through the treated animal?

The correct choice refers to systemic pesticides specifically designed for use on animals that are absorbed into their bodies and distributed throughout their systems. These pesticides can effectively control parasites or pests that affect the treated animal by moving through its bloodstream or tissues.

Systemic action allows for the pesticide to remain effective over an extended period, providing ongoing protection as it continues to circulate within the animal. This characteristic is particularly advantageous when dealing with pests that may attach to or infest the animal at various stages in their lifecycle.

In contrast, fumigants are gases that penetrate materials to control pests but do not circulate through an animal's body. Microencapsulated pesticides are formulated to release active ingredients over time, but this does not necessarily imply they are designed for absorption into living animals. Impregnates generally refer to pesticides that have been infused into a substrate or surface, which also does not imply systemic absorption and circulation within an animal.