It seems that you have missed to include the necessary options for this question so I had to look for it. Here is the answer. The one that lymphoid cells traps antigens and transport them to lymph nodes are the T LYMPHOCYTES. Hope this answers your question.
Vacuole. Amoeba is a unicellular organism formerly grouped under Kingdom Protista. Amoeba in freshwater need contractile vacuole to control input and output of water. (osmosis). Without this structure, ameboid cells will be filled with water and eventually burst.
Other reasons are
Not finishing the antibiotics.
Or
Taking antibiotics too often