Final answer:
Asthma allergens typically enter the body via inhalation and can cause an immediate hypersensitivity reaction resulting in inflammation of the airways.
Step-by-step explanation:
The allergens that cause asthma primarily enter the body through inhalation. When individuals with asthma inhale certain substances like pollen, pet dander, or dust mites, these allergens can trigger an inflammatory response in the airways, leading to symptoms such as coughing, wheezing, and difficulty breathing. Allergy to pollen is classified as an immediate hypersensitivity reaction, which is a type of allergic reaction that occurs soon after exposure to an allergen and is mediated by IgE antibodies.