To accurately identify a sentence that contains an example of contested usage, I would need to see the specific sentences you're considering. Contested usage generally refers to usage in language that is debated regarding its correctness or appropriateness.
For instance, a sentence like "Everyone should bring their own lunch" may be contested because some grammarians argue that "everyone" is a singular pronoun and should use a singular pronoun (e.g., "his or her").
If you provide some sentences, I can help identify the one that exemplifies contested usage!