The T Cell Receptor (TCR)complex Differs from an Immunoglobulin Molecule

The T cell receptor (TCR) complex differs from an immunoglobulin molecule in which one of the following ways?

A) On average,a TCR binds antigen with much lower affinity than does an Ig molecule.
B) The TCR can serve as a lymphocyte antigen receptor,but an Ig molecule cannot.
C) Only the TCR can bind soluble antigen directly.
D) The TCRs expressed by one clone of T cells can undergo changes in constant region structure after cellular activation,whereas Ig molecules expressed by one clone of B cells do not.
E) The TCR polypeptide chains have short cytoplasmic tails and rely on associated proteins for signaling functions,whereas membrane Ig receptors are competent signaling molecules on their own.