Clusters of twisted strands of β sheet are called: (A) Amphiphatic helices, (B) β barrels, (C) Loops and bends, (D) Supersecondary structures
Answer is B. Most β sheets are not perfectly flat but tend to have a right-handed twist. Clusters of twisted strands of β sheet, sometimes referred to as β barrels, form the core of many globular proteins.
Ref: Harper’s illustrated biochemistry. 30th edition page no: 39