The revision that corrects the faulty parallelism in the sentence is: "Margot prefers watching a hockey game to watching ice skating performances."
Option B is correct.
Both verbs should be in the gerund form in order to create parallelism in the sentence.
Parallelism refers to the use of components in a sentence that are grammatically equal; or alike in their construction, sound, meaning, or meter. Parallelism is often referred to as one of the basic principles of grammar and rhetoric