This question presents a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise, choose one of the others.
The potential hazards of certain compounds, including dimethylmercury, is such that even the strictest observation of safety protocols are often insufficient to fully prevent potential incidents.