Which of the following diseases is caused by a parasite?

Malaria

The correct answer is Option (4)-Malaria

Malaria is caused by a parasite, specifically the Plasmodium parasite, which is transmitted to humans through the bite of infected female Anopheles mosquitoes. Once inside the body, the parasites multiply in the liver and then infect red blood cells, leading to symptoms such as fever, chills, and flu-like illness. Other options listed—plague, pneumonia, and goiter—are caused by bacteria, viruses, or iodine deficiency, respectively.