In the overview of DNA replication, what is the primary role of helicase at the replication fork?

• A. It synthesizes short RNA primers to provide a 3′ OH for DNA polymerase to extend.
• B. It unwinds the parental DNA double helix by breaking hydrogen bonds between complementary bases.
• C. It adds nucleotides to the growing DNA strand in the 5′ to 3′ direction using the template strand.
• D. It joins Okazaki fragments together by forming phosphodiester bonds in the sugar-phosphate backbone.

Answer: (B)