Final answer:
The complex formed when dsDNA melts and the strands separate is called a replication fork, which is formed by the activity of helicase. 3)Single-stranded binding proteins prevent premature reannealing of the DNA strands.
Step-by-step explanation:
When dsDNA (double-stranded DNA) melts and the strands separate, the complex formed is called a replication fork. The separation of the DNA strands is carried out by the enzyme helicase, which unwinds the DNA at the origin of replication. This allows for the replication process to occur. Single-stranded binding proteins coat the DNA around the replication fork, preventing the strands from reannealing prematurely. These proteins stabilize the single-stranded DNA and ensure that the replication process proceeds smoothly. Therefore, the correct answer is option 3) Single-stranded binding proteins.