Final answer:
DNA replication occurs in the order of unwinding the DNA helix by DNA Helicase, base pairing of complementary nucleotides, and then joining the nucleotides to form new DNA strands.
Step-by-step explanation:
The correct order in which DNA replication occurs is: unwinding, base pairing, joining. This process begins with the unwinding of the DNA helix, generally known as the process of 'unzipping,' which is accomplished by the enzyme DNA Helicase. Once unwound, base pairing occurs wherein complementary nucleotides are attached to each of the single-stranded DNA. The final step involves the joining of these nucleotides to form a continuous new strand, which is carried out by DNA polymerase III, and the sealing of the gaps by DNA ligase. Hence, the correct sequence based on the options given to the question is (b) Unwinding, base pairing, joining.