During initiation of translation in prokaryotes, multiple AUG codons in the same cistron (coding sequence) may be utilized because: a. only initiator AUG codons are preceded by a Shine-Dalgarno ribosome-binding sequence. b. all AUG codons are preceded by a Shine-Dalgarno ribosome-binding sequence. c. scanning of the 5′UTR by the preinitiation complex requires ATP hydrolysis. d. the 5 ' cap structure is involved in ribosome binding.