Concept:A disease vector is an organism that carries and transmits a pathogen from one host to another.Explanation:Malaria is caused by the microorganism Plasmodium.Female Anopheles mosquitoes carry this parasite and inject it into humans when they bite.So the mosquito acts as a vector transmitting malaria.None of the other options describes a vector transmitting a disease.Answer:B. Mosquito transmitting malaria.