Answer: A. She will either go to the party or stay home and rest.
Step-by-step explanation:
Using parallel structure means phrasing words in a sentence to show that the options/ ideas mentioned are equally important. Usually, this structure is seen when the options are joined by coordinating conjunctions such as "and" or "or'' and ''either ... or.''
In the sentence above, the options of going to the party and staying home to rest are both equally important and are connected by ''either ... or'' so this sentence uses a parallel structure.