20. Which of the following statements is correct regarding upstream open reading frames(uORFs)?
(A) uORFs can be found in both eukaryotes and prokaryotes.
(B) uORFs can be found in both 5' and 3' untranslated regions.
(C) The presence of uORFs typically causes an increase in protein expression.
(D) Translation of the open reading frame (ORF) encoding the yeast activator Gcn4 isinhibited when amino acids are deficient, because the ribosome moves slowlyalong the uORFs and then dissociates.
(E) The size of uORFs is typically more than 20 codons.