With which of the following statements concerning the stiffening of aging tissues would the author most likely agree
A．It paradoxically both helps and hinders the longevity of proteins in the human body.
B．It can be counteracted in part by increased ingestion of glucose-free foods.
C．It is exacerbated by increased enzymatic glycosylation.
D．It probably involves the nonenzymatic glycosylation of proteins.