Which word has a negative connotation and refers to something harmful?

The word "detrimental" is the correct choice because it specifically refers to something that causes harm or damage. It has an inherent negative connotation, indicating adverse effects or an unfavorable outcome. In contrast to the other options, which suggest positive outcomes or an absence of strong connotation, "detrimental" clearly expresses a harmful nature.

For instance, "beneficial" and "advantageous" imply positive impacts or benefits derived from actions or situations, while "neutral" suggests a lack of bias or effect altogether. Therefore, "detrimental" stands out for its explicit association with harm and negative consequences.