Why might an author use irony in a literary work?

to summarize the events and characters
to emphasize important themes
to promote the use of a particular setting
to motivate the reader to use reference materials

Must read story will give if ! in “perseverance,” which theme is reflected in the lines, “life’s field will yield as we make it / a harvest of thorns or of flowers”? a: life is a field in which flowers and thorns will grow. b: accept what you are given, because you cannot change it. c: your life is the result of the work you put into it. d: working together people achieve their goals in life.