Which one of the following diseases is caused by protozoans?
(a) Malaria
(b) Influenza
(c) AIDS
(d) Cholera
Answer: The correct option is (a) Malaria
Solution: Influenza is caused by an infectious agent called Influenza Virus. It is transmitted by infected people when they sneeze or cough releasing the virus in the air, which in turn is inhaled by a non-infected person and causes the infection.
AIDS is caused by the Human Immunodeficiency Virus (HIV) and is transmitted by sexual contact, blood-to-blood contact (blood transfusion) with an infected person where the body fluids are exchanged with the non-infected person.
Cholera is caused by the bacterium Vibrio Cholerae and is transmitted by ingesting contaminated water or food.
Malaria is caused by the protozoan microbes called Plasmodium vivax and transmitted by female Anopheles Mosquitoes.
Hence, A is the correct answer.