The sentence that maintains parallelism is option D) “Gilb writes from his perspective as a Mexican-American, a parent, and a Southwesterner”. Parallel structures bring coherence to a text by using the same grammar pattern when listing things. In this example, the grammar structure that is used to reflect parallelism is a noun after the word “as” such “Mexican-American”, “a parent” and “a Southwesterner”. In the rest of the options there is a break in the grammar pattern since they do not follow the same structure as in option C) that starts by listing with nouns “Mexican-American” and “parent” but then it uses verb to be+ing and a prepositional phrase.
Parallel structures are useful writing resources since the reading experience for the reader is smoother and easier to understand.
Facts are things or events that have actually occurred and can be proven. An opinion is a person's belief or thoughts on a certain thing or event. I hope this helps!