Answer:
4, 3, 1, 2
Step-by-step explanation:
FIRST: cDNA is synthesized to be used as a gene of interest: processed (spliced) mRNA (no introns) is reverse transcribed to cDNA using reverse transcriptase, an enzyme from retroviruses
SECOND: Restriction enzyme used to cut GOI
THIRD: Same Restriction enzyme used to cut plasmid (sticky ends are created)
FOURTH: GOI connects/hybridizes with plasmid due to base-pairing
FIFTH: DNA ligase connects the recombinant DNA strands