Final answer:
The correct answer is A) Promoter, Ribosome Binding Site (RBS), as a promoter facilitates transcription initiation and the ribosome binding site is essential for correct alignment of the ribosome for translation of mRNA into protein.
Step-by-step explanation:
Expression vectors must contain certain genetic elements to facilitate the proper transcription and translation of the inserted gene. One of these critical elements is a promoter, a DNA sequence to which RNA polymerase and associated factors bind and initiate transcription. A promoter is typically found upstream of the coding sequence of the gene it regulates. The reading frame is another essential feature that ensures the resulting mRNA can be correctly translated into protein by ribosomes. For correct translation to occur, a Ribosome Binding Site (RBS) is also necessary, which precedes the translation start codon in prokaryotes.
Therefore, the correct answer to the student's question is: A) Promoter, Ribosome Binding Site (RBS). A promoter allows RNA polymerase to initiate transcription, and a ribosome binding site helps to align the ribosome for proper translation initiation.