Read the passage and answer the following question.

Rahul went for a vacation along with his friends to a town located in countryside during summers. The house on which they stayed was surrounded by farmland by all sides. Lots of crops was growing nearby and Rahul was very excited to visit the crop fields. He went to the fields along with his friends and spent 2 to 3 hours in the fields. On returning back Rahul had running nose, watering eyes and continuous sneezing which was very frequent. the symptoms worsened with time.

Out of the following which is an example of allergen? (Question 4)

All of the above

The exaggerated response of the immune system to certain antigens present in the environment is called allergy. The substances to which such an immune response is produced are called allergens. The antibodies produced to these are of IgE type. Common examples of allergens are mites in dust, pollens, animal dander, etc. Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing.