Question

When DNA replicates, the first step is

O proteins move along the DNA and "read" the code
DNA polymerase adds new nucleotides to the old strands
a proofreading enzyme checks to see if there are errors in the order of the nucleotides
the double helix is opened down the middle by an enzyme called helicase

Answer 1

answer; the double helix is opened down the middle by an enzyme called helicase

this is because the DNA needs to be opened first before any proteins start reading or coding.