When an antigen is introduced into the body, how long does the patient remain sensitized?

The correct answer reflects the nature of sensitization in the immune response. When an antigen enters the body, it stimulates the immune system to produce specific antibodies that can recognize and bind to that antigen. The patient remains sensitized for as long as these antibodies remain attached to the antigen or continue to circulate within the body.

Sensitization implies that the immune system has "learned" to recognize the antigen, and this memory can last much longer than a temporary attachment or a short timeframe. In many cases, once sensitized, the immune system can respond more rapidly upon subsequent exposures to the same antigen, indicating that the antibodies or memory cells remain present for an extended period, beyond just a few minutes or hours.

The other options suggest timeframes that are much too short for the persistence of sensitization in the immune system. Typically, sensitization can last for days, weeks, or even longer, depending on the type of antigen and the individual's immune response. This characteristic is crucial for understanding how allergies and immune responses work, as the presence of antibodies indicates ongoing sensitization to specific antigens.