Final answer:
T cell receptors, immunoglobins (antibodies), and the major histocompatibility complex (MHC) all directly interact with antigens during the adaptive immune response; hence, the correct answer is D. all of these.
Step-by-step explanation:
The proteins that interact directly with antigens during the adaptive immune response are:
- T cell receptors (receptors on T cells)
- Immunoglobins (also known as antibodies)
- Major histocompatibility complex (MHC)
Therefore, the correct answer to the question is D. all of these. Each of these proteins plays a role in recognizing and binding to antigens: T cell receptors bind to antigens presented with MHC molecules on the surface of antigen-presenting cells, immunoglobins can be found on the surface of B cells or secreted into the blood, and the major histocompatibility complex presents processed antigen fragments to T cells. The interaction with these antigen-specific receptors is critical for the activation and regulation of adaptive immune responses.