Which of the following is not a suitable method to prevent allergy.

The correct option is C Need to vaccinate against the pathogen.

• There is no permanent cure for allergies. What we can do to prevent allergic reactions is:

(i) Avoid all the allergens completely to which you are sensitive.

(ii) Take allergy shots for seasonal allergies caused by pollen.

(iii) In case of food allergy, please read the labels on the food packet before buying.

(iv) Know your allergen i.e. one should know which particular substance triggers an immune response.

• Vaccination is to provide immunity against pathogenic infections, not allergies.

So, the correct answer is option D.