How do you think posters can help us better understand a historical time period?

They tell about the time and event.

Explanation:

Depending on the poster, it can tell more about the time it's from. The style might say it's from a certain century, it was for a certain event, etc. For example, if a poster was an advertisement for a new ballet playing, then it would've been from the time when the ballet was new.

there has only been 12 presidents. the 12th president is/was moon jae-in

the answer is b: an economic crisis throughout the country.