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.
In a small-scale pilot study of psilocybin's use in cases of treatment-resistant depression, they established that the compound, which is the psychedelic component in so-called "magic" mushrooms, is safe and effective; meaning that it may one day be an effective treatment for patients with severe depression that do not respond to other therapies.