Question

you are infected with a new bacterial strain that you hadn’t caught before, but your immune system recognizes nonself proteins on this strain’s surface from a previous infection you had by a different strain of bacteria. which of the following is true about your body’s immune response?
because your immune system recognizes the nonself proteins, it is taking advantage of passive immunity.
because your immune system recognizes the nonself proteins, a secondary immune response is initiated.
because this is a new pathogen, a primary immune response will be activated.
because this is a new pathogen, the innate immune system will be most important in defeating this infection.

Explanation:

The immune system recognizes nonself proteins from a prior infection, indicating memory cells (from primary response to the previous strain) are present. A secondary immune response is faster/stronger, triggered by recognition of familiar antigens. Passive immunity involves external antibodies (not here). Primary response is for first-time antigen exposure (not the case here). Innate immunity is non-specific, but adaptive (secondary) is key with prior antigen recognition.

Answer:

Because your immune system recognizes the nonself proteins, a secondary immune response is initiated.