試題詳解

26. Primary lymphoid tissues are the sites where lymphocytes________，whereas secondary lymphoid  tissues are the sites where lymphocytes ______ .
(A) are stimulated； develop and mature
(B) undergo clonal selection； differentiate from hematopoietic stem cells
(C) encounter pathogens； undergo apoptosis
(D) die； are phagocytosed after death
(E) develop and mature； become activated