Question

What aspect of Lady Bracknell’s behavior does Wilde use to poke fun at the importance placed on frivolous events in formal society? her concern with a party instead of Mr. Bunbury’s health her interest in playing classical music at her reception her jealousy over Algernon’s friendship with the sickly Mr. Bunbury her concern about the health of Algernon’s friend

Answer 1

The aspect of Lady Bracknell's behavior that Wilde uses to poke fun at the importance placed on frivolous events in formal society is her concern with a party instead of Mr. Bunbury's health.
Wilde made fun of Victorian society in his play "The Importance of being Earnest" and Lady Bracknell was the epitome of that kind of society and behavior. 

Answer 2

The correct answer is - her concern with a party instead of Mr. Bunbury’s health.

Oscar Wilde's The Importance of Being pokes fun at the Victorian society which placed too much importance of irrelevant things. He is using the character of Lady Bracknell to depict this mockery - she is concerned with her party going splendidly instead of worrying about another person's health. The frivolousness of her concern is similar to the general spirit of the Victorian era.