Explanation.
Remember that before the cell decides to enter a mitotic process, there is an interphase phase called S or synthesis phase where the DNA is replicated.
On the other hand, remember that the semiconservative DNA replication in the cell involves a number of different enzymes and other proteins and it takes place in two steps:
1. The DNA is unwound to separate the two template strands.
2. New nucleotides are linked by covalent bonding to each growing new strand in a sequence determined by complementary base pairing with the bases on the template strand.
Thus, we can conclude that the correct answer is:
Answer:
Enzymes unzip strands of DNA.