本题目来源于试卷: Interaction & Interdependence C.7 Defence Against Disease，类别为 IB生物学
[单选题]
The graph shows how the l:zl/wru)sj 3 number of antibodies ltbd49 ct0g) l t+d-us changed in an individual's blood ove su4b -lddgtl 0t9+)c tr time. 
A. Primary infection
B. Secondary infection by the same pathogen
C. Infection by a different pathogen
D. Antibiotics administered
参考答案: B
本题详细解析:
A second infection by a pathogen triggeiy*d+ nmh gm )-9q;0qz k1isomrs a much faster and more potent immune response, resulting in the production of greater levels of antibodies (Choice B), when compared to primary infection. Primary infection caiis-mo dn19zm+y; kq )m*ghq0 uses a smaller increase in antibody numbers; this is represented by Y (Choice A). Infection by a different pathogen (Choice C) would cause a raise in antibody numbers similar to levels in point Y. Antibiotics do not increase antibody numbers (Choice D).
| 
