which of the statements describe how inducers cause changes in gene expression?
a. inducers bind to activator proteins and enhance the ability of the activator to bind DNA
b. inducers enhance transcription of all genes
c. inducers are ions that are essential for the function of RNA polymerase
d. inducers allow transcription of specific genes
e. inducers are small molecules that bind to DNA to enhance transcription of target genes