Answer:
The two sentences that correctly use parallel structure are the following ones: "Bernie not only forgot his one-year anniversary with Rachel but also he missed his father's birthday" and "Stan is a voracious reader, an expressive writer, and a skillful painter".
Step-by-step explanation:
Parallelism, also called parallel structure, is the repetition of a chosen grammatical structure within a sentence. When you use parallel structure, you add clarity to your writing. In the case of the sentences above, parallelism has been created by means of the use of the cordinating and correlative conjunctions. With the correlative conjunction, the two clauses follow the same grammatical structure (a transitive verb in the past simple tense) and, with the cordinating conjunction, an adjective premodifies each of the coordinated NPs (voracious reader, expressive writer, skillful painter).