Allergy is an immune system overreaction to allergens like pollen, dust, and certain foods.
Allergy is an exaggerated immune response to normally harmless substances such as pollen, dust, or certain foods.
Examples:
(b) Order of the differential equation: $ 5x^3 \frac{d^3y}{dx^3} - 3\left(\frac{dy}{dx}\right)^2 + \left(\frac{d^2y}{dx^2}\right)^4 + y = 0 $