If You Were Developing Artificial B-Cell Receptors (BCRs)based on the Natural

If you were developing artificial B-cell receptors (BCRs) based on the natural version and wanted to change the BCRs' ability to bind certain antigens,which region of the natural receptor would you alter?

A) transmembrane domain
B) amino terminus of light and heavy chains
C) carboxy terminus of light and heavy chains
D) the region projecting into the cytoplasm of the cell