Dramatic irony is only found in plays.

the manager emerges. taking marlow aside, he says they have done all they can for kurtz. he adds that kurtz did more harm than good for the company. his actions were too "vigorous" for the moment. the manager says that kurtz was unethically gathering ivory by exploiting the locals. this, of course, is rather ironic coming from a guy who makes his living by exploiting the locals in the worst ways.

explanation:

the correct answer is a.

since in the sentence the word beacon is used as "guide".

lighthouse:

high tower located on the coasts and ports that emits a powerful light at intervals to guide navigators at night.

luminous tower.

beacon synonyms as a guide: lighthouse, north, tower