What are the two primary vector mosquito species of malaria in North America north of Mexico?

• A. Anopheles quadrimaculatus and Anopheles gambiae
• B. Anopheles quadrimaculatus and Anopheles freeborni
• C. Anopheles quadrimaculatus in the eastern states and Anopheles freeborni in the west
• D. Anopheles albimanus and Anopheles darlingi

Answer: (C)

Two main malaria vector species in the United States north of Mexico are Anopheles quadrimaculatus in the eastern states and Anopheles freeborni in the western states. This regional pairing reflects historical evidence that these two species were the primary vectors in their respective areas, tied to where they are most abundant and effective at transmitting Plasmodium to people.

Other options include species not native to North America or fail to match the eastern-versus-western distribution, such as African or tropical American species. The best answer precisely assigns each species to its region, capturing how malaria transmission historically occurred across the U.S.