Concept:Trypanosomiasis is transmitted by a blood-sucking insect vector.Explanation:Trypanosome is a protozoan parasite that causes sleeping sickness.It lives in the blood of an infected host.When a tsetse fly bites an infected person, it picks up the parasite.The fly transfers the parasite to a healthy person during its next bite.Therefore, the tsetse fly acts as the vector for trypanosome.Answer:D. tsetse fly