The reader must understand that they are at the mercy of the author’s imagination.
What’s wrong with the sentence above? Some might say there is nothing at all is wrong with it. Others, however, will take issue with the use of ‘they,’ a plural pronoun, in place of the singular ‘reader.’ How can this sentence be corrected? Some would use ‘he’ in place of ‘they,’ with the understanding that masculine pronouns are a stand-in for proper nouns of either gender.