28. Which of the following statements is correct regarding riboswitches?
(A) Most riboswitches are trans-regulatory elements.
(B) Riboswitches can regulate gene expression at both transcriptional andtranslational levels.
(C) The riboswitch region that binds the small-molecule ligand is called the receptor.
(D) Riboswitches are typically found downstream of genes involved in the synthesisof the metabolite ligand recognized by the riboswitch.
(E) Riboswitches can mediate rho-dependent transcription termination.