text: An<unk>  is a nonparasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals.
  Most humans mount significant IgE responses only as a defense against parasitic infections. However, some individuals mount an IgE response against common environmental antigens. This hereditory predisposition is called atopy. In atopic individuals, non-parasitic antigens stimulate inappropriate IgE production, leading to type I hypersensitivity. 
  Sensitivities vary from one person to another and it is possible to be allergic to an extraordinary range of substances.
option_0: Allergen
option_1: Inhalant
option_2: Tobacco
option_3: Phytochemical
option_4: Marine toxins
option_5: Food additive
option_6: Generic drug
option_7: Antigen