Final answer:
The correct option is a. puppet metaphor. Bernays uses the puppetmaster metaphor to describe the relationship between propaganda creators and the common people.
Step-by-step explanation:
The metaphor that Bernays uses to describe the relationship between those who create propaganda and the common people is the puppetmaster metaphor.
Bernays compares propaganda creators to puppetmasters, asserting that they use various techniques to manipulate and control the thoughts and actions of the masses, much like a puppetmaster controls puppets.