Allostery is best defined as:
a) the ability of a protein to recognize a particular sequence in DNA.
b) the ability of a receptor protein to bind several different steroid hormones.
c) a conformational change induced at one site in a protein by a ligand binding at a different site.
d) the ability of a repressor to shut off transcription by binding it to an operator.
e) change in gene regulation inside a cell, in response to changing conditions in its environment.