Answer:
The correct answer is a. Helicase unwinds DNA
Explanation:
DNA replication is a process in which DNA make it's own copy. There are several enzymes and factors which access the DNA replication process like helicase, primase, SSB protein, DNA polymerase etc.
The first step in DNA replication is the unwinding of double stranded DNA which is accomplished by an enzyme called Helicase. Helicase opens up the double stranded DNA at replication fork by breaking the hydrogen bond between the nucleotides of complementary strands.
This provides a single stranded template for DNA polymerase to form a new complementary strand. In E. coli Dna B is the primary helicase and in humans the primary helicase is MCM( minichromosome maintenance protein complex).