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) encounter pathogens； undergo apoptosis
(C) develop and mature； become activated
(D) undergo clonal selection； differentiate from hematopoietic stem cells
(E) die； are phagocytosed after death