Which of the following must happen first in order for DNA replication to occur?

DNA polymerase binds to the leading strand

DNA is unwound

Hydrogen bonds form between bases

chromosomes condense

Answer: DNA is unwound.

Explanation:

DNA replication is the process where by two identical DNA copies are produced from a double stranded DNA molecule.

Before DNA will replicates, the double helix length of the DNA to be copied must be unwound, the two strands are separated and the hydrogen bond that link the paired bases are broken. Once the are unwound, they are held apart to expose the new bases so that hydrogen bond can link the nucleotides. The enzyme polymerase then join the new nucleotides into a new DNA strand that is complementary to the template.