The correct option is
D Allergy
Hay fever (allergic rhinitis) is caused by grass pollen mostly but it can also be caused by tree pollen or weed pollen. Pollen is a fine powder enriched in protein released by plants as part of their reproductive cycle which can cause irritation in nose, eyes and throat. Symptoms of hay fever include sneezing, runny nose, itchy eyes etc. It is more common in spring and early fall. Hepatitis and dengue are viral diseases. Helper T-cells are immunity providing cells in the body
So, the correct answer is 'Allergy'