Which of the following would be a BCR?

CD4

MHC II

MHC I

IgD

The correct answer is option - IgD.

Explanation:

BCR or B - cell receptors are the antigen-specific receptors with different specificities but their function depends on the T cells however their activation does not rely on T cells.

IgD and IgM are BCR for the naive mature B - cells. These are membrane-bound monomeric forms with 2 heavy chains and 2 light chains. There are more than 100000 BCRs present on every Naive mature B - cell.

Thus, the correct answer is option - IgD