In Cooperative DNA Binding,the Binding of

In cooperative DNA binding,the binding of

A) both proteins must occur at the same time.
B) one protein molecule is more favored when another one is bound to a nearby site on the DNA.
C) one protein molecule is less favored when another one is bound to a nearby site on the DNA.
D) one protein molecule is only possible if two other molecules are bound to a nearby site on the DNA.