A child was exposed to the hepatitis A virus, became ill, and made a full recovery 2 years ago. The child is now immune to the hepatitis A virus and will likely be protected for the rest of her life. This type of immunity is referred to as

  1. active artificial immunity.
  2. naturally acquired active immunity.
  3. artificially acquired passive immunity.
  4. naturally acquired passive immunity.
Number 2 is correct.
Rationale: Naturally acquired active immunity occurs when a person is exposed to a pathogen and develops an immune response. This immune response will lead to immunological memory, thus protecting the person from illness if exposed to the same pathogen again in the future. Naturally acquired passive immunity occurs when antibodies are passed from an immune mother to her baby through breast milk or the placenta. Artificially acquired immunity is immunity acquired from vaccine sources.