Answer:
C. Surface antigens on the type B blood cells resembled the surface antigens on the bacteria.
Step-by-step explanation:
In this scenario, having blood type B meant that the surface antigens on the individual's red blood cells resembled those on the Yersinia pestis bacteria. This similarity might have led to a slower immune response because the immune system may not have recognized the bacteria as foreign as quickly as it would have with a different blood type.