The parallel structure of a sentence implies the use of words or phrases carrying equal significance. As per the given question, none of the examples displaying a parallel construction as they fail to follow a similar structure(ideas of equal importance). As per the grammatical rules, while following a list in a sentence(as given in the question), each part must carry a similar form or tense of the verb. Therefore, the correct version of the given sentence would read as:
'Each of the stories has <u>strong protagonists</u>, <u>timeless themes</u>, and <u>realistic conflicts</u>.'
