Final answer:
CD3 is the CD antigen associated with the T cell receptor (TCR). CD3 is critical for T cell activation and is part of the TCR complex that recognizes antigens presented by MHC molecules.
Step-by-step explanation:
Among the CD antigens associated with the T cell receptor (TCR), CD3 is the correct answer. The TCR complex on T cells is responsible for recognizing antigens presented by MHC (Major Histocompatibility Complex) molecules, and the CD3 molecule is a critical part of the TCR complex.
It plays a key role in T cell activation and signal transduction. Unlike CD3, other CD molecules like CD4 and CD8 are involved in enhancing the interaction between T cells and antigen-presenting cells, but they are not directly part of the TCR structure.