Enhancers and promoters are ______. In contrast, the heterodimer "TFIIA and TFIIB" are examples of __________.
a. trans-acting elements, cis-acting factors
b. cis-acting elements, trans-acting factors
c. cis-activating factors, trans-acting elements
d. trans-activating factors, cis-acting elements
I believe the answer is "d" but don't have anything to back it up. Please help.