Answer:
It is difficult to determine what persuasive technique a poster uses without seeing the poster in question. Posters often use persuasive techniques such as the call to action, authority, empathy, and trust to promote a certain behavior or idea.
They can use different persuasive techniques to promote handwashing, such as showing pictures of people washing their hands and providing clear instructions on how to do it correctly. They can also use the call to action to encourage people to wash their hands frequently.