Answer:
One example in "Sense and Sensibility" where Jane Austen uses Dramatic Irony is the scene where Lucy Steele informs Elinor Dashwood that she has been secretly engaged to Edward Ferrars for the past several years. This shows the readers that Elinor has great affection for Edward but is unsure about Edward's feelings, therefore the revelation by Lucy is the answer to Elinor's confusion about Edwards true feelings.
Explanation:
Dramatic Irony is a literary device in which a character does not understand the implication of a particular action or event of dialogue but the reader or the viewers does.
The revelation by Lucy above shows that Lucy has an inkling that Elinor is interested in Edward, therefore she tries to manipulate and deceive her into opening up. but Elinor did not fall for the trap. Although the situation gives the readers the opinion that Lucy has left Elinor a puzzle to solve regarding Edward Ferrars.