Significant reduction in the platelet count of human blood is the main symptom of this disease.

The correct option is B Dengue

• Dengue is caused by the dengue virus which is transmitted through infected mosquitoes to humans.
• The major symptom of this disease is the reduction in the platelet count in the human blood.
• Dysfunction of the bone marrow due to infection of the stromal cells leads to reduced numbers of platelets.
• The other symptoms are fever, rash, swollen gums and glands, muscle and joint pain.
• Thus, the correct answer is option B.