• This is a subtle nuance of "The + Superlative." While "The youngest employees" is grammatically okay in isolation, often in these specific exam patterns, the error lies in the context of the sentence's logic or a missing determiner. However, looking at the provided answer key (A), it suggests a specific stylistic or structural preference by the examiner—likely that the sentence doesn't require a superlative if only two groups are being compared, or "young" should be used. Note: In standard English, A is often considered correct, but in the context of this specific key, they likely preferred "Young employees."
