Read the excerpt from The Importance of Being Earnest.
Jack. It pains me very much to have to speak frankly to you, Lady Bracknell, about your nephew, but the fact is that I do not approve at all of his moral character. I suspect him of being untruthful. [Algernon and Cecily look at him in indignant amazement.]
Lady Bracknell. Untruthful! My nephew Algernon? Impossible! He is an Oxonian.
How does Lady Bracknell's defense of Algernon advance the plot?
It leads to Cecily withdrawing her acceptance of Algernon's proposal.
It leads to Cecily becoming upset with Algernon for lying.
It causes Jack to refuse to allow Cecily to become engaged to Algernon.
It causes Jack to reveal that Algernon broke into Jack's home by pretending to be his brother.