Final answer:
The BCR, or B-cell receptor, that would be a BCR is the IgG antibody. IgG antibodies are produced by B cells and can bind to specific antigens, triggering an immune response.
Step-by-step explanation:
The BCR, or B-cell receptor, is a key component of the immune system and is responsible for recognizing antigens. Out of the options given, the BCR would be the IgG antibody (c). IgG antibodies are produced by B cells and can bind to specific antigens, triggering an immune response. MHC class I (a) and CD8 receptor (b) are both involved in antigen presentation to cytotoxic T cells, while TLR-4 receptor (d) is involved in recognizing bacterial pathogens. Therefore, the correct answer is c) IgG antibody.