In DNA, the enzyme which breaks the H₂ bonds is

The correct option is Helicase.

In DNA replication and other processes involving double-stranded DNA, the two strands must be separated to allow the genetic information to be read. The two strands of the DNA double helix are held together by hydrogen bonds between complementary base pairs (Adenine pairs with Thymine, and Cytosine pairs with Guanine).

The enzyme responsible for breaking these hydrogen bonds is Helicase. As DNA helicase moves along the DNA molecule, it uses the energy from ATP hydrolysis to unwind the double helix and separate the two strands, creating a replication fork.

Let's briefly review the roles of the other enzymes mentioned in the options to understand why they are not correct for this specific function:
1. Ligase: This enzyme joins DNA strands together by catalyzing the formation of phosphodiester bonds, sealing nicks in the sugar-phosphate backbone.
2. Topoisomerase: This enzyme helps relieve the torsional strain and overwinding (supercoiling) in the DNA double helix ahead of the replication fork by transiently cutting and rejoining the phosphate backbone.
3. Polymerase: This enzyme synthesizes new DNA strands by adding nucleotides complementary to the template strand.