Can someone tell me where to place commas? i forgot because i never used to put it

the service industry in the united states grew in the late 1800s. what was one effect of that growth?

the number of people with jobs in factories as unskilled workers decreased.

the number of people with jobs in factories as unskilled workers increased.

the middle class grew as people took jobs as clerks, lawyers, and teachers.

the middle class shrank as people left jobs as clerks, lawyers, and teachers.

dramatic irony occurs when the reader/audience knows more about a character's situation than the character does. the one main effect is that it gives the reader a sense of superiority, or detached superiority. the reader not only seemingly discovers what is revealed, but feels superior for doing so.