Which sentence best revises sentence 3 to use formal
language?
it focuses on one main character and one main plot
event.
that is, short stories just look at one character and one
thing
it talks about one main character and one important
thing that happens.
what i mean is it centers on a main character and a
single plot occurrence.

It focuses on one main character and one main plot  event.

Explanation:

Scout and Dill are close friends who spend their summers together and share many memorable experiences. Scout recalls meeting Dill for the first time in the opening chapter when he visits his Aunt Rachel in Maycomb. Scout and Dill become fast friends and spend the majority of the summers playing, performing, and raiding the Radley yard.