B..............................
I think both of them are positive feedback
Macrophages
Using the receptors on their surface and through the facilitation by immunoglobulins that attach to the foreign matter, macrophages 'hold' the foreign bodies in the body and 'ingest' them through phagocytosis. Lysozymes in the cells then in 'digest' the foreign matter.
D) TATCCG. The complementary code for "A" is always "T" and for "G" it is "C"