Why is everyone but Mattie and Mother Smith skeptical of Mattie's plan to reopen the coffeehouse?

relative clauses are either restrictive or nonrestrictive depending on the type of information they add to the noun they modify. restrictive relative clauses introduce information which is considered essential for the sentence to make sense and present a clear idea. they are not set off with commas. on the contrary, nonrestrictive relative clauses provide information which is not relevant to the meaning of the sentence and therefore can be dropped without altering its meaning. what is more, they are set off with commas.

a) rami malek, who starred in the tv show mr. robot, is the one to play freddie mercury in bohemian rhapsody = rami malek is the one to play freddie mercury in bohemian rhapsody (the same meaning as the first sentence)

b) isn't that the boy who lives in your neighbourhood?

isn't that the boy in your neighbourhood? (different meaning. you cannot identify which boy the speaker is talking about)