This image would have been found during what 20th century event?

I think this is a Chinese propaganda poster showing members of the student-led Red Guards social movement (Hóng Wèibīng) during the Cultural Revolution in China (1966 - 1976).

"girls"

explanation:

a subject of a sentence is a noun or pronoun that shows who/what is performing the action (or verb) of the sentence.

in this case, the sentence states that the girls see. the girls are the ones who are performing the action, so they are the subject.

hope this !