Final answer:
The error in the sentence is parallelism. The corrected sentence should read 'Monica is attractive, intelligent, and hardworking.' Editing for clarity involves revising mixed constructions and ensuring parallel structure.
Step-by-step explanation:
The sentence 'Monica is attractive, intelligent, and tries hard.' contains an error in parallelism. Each item in a list within a sentence should be in the same grammatical form, also known as parallel structure. To correct this, the sentence should maintain a consistent use of adjectives: 'Monica is attractive, intelligent, and hardworking.' In this revised sentence, all the qualities describing Monica are adjectives, which resolves the parallelism issue.
When editing for more effective sentences, it's important to ensure clarity, coherence, and proper syntax adherence. Sentences should be free of unnecessary passive voice, subject/verb agreement errors, comma splices, and should properly capitalize titles, names, and events. Editing for clarity often involves revising mixed sentence structures for better readability and rhetorical effectiveness.