An enzyme that breaks DNA, dispels the tension, and reseals the strand ahead of a DNA replication growing fork is called a(n):

Topoisomerase

Explanation:

Topoisomerases are enzymes that produce changes in the topology of the DNA during replication, transcription, traduction, or reparation processes. They can cut one or both strands and in order to relieve torsional stresses in the supercoiled structure of DNA. With this, they help to maintain the chromosome's integrity. There are two types of topoisomerases: topoisomerase I (it cuts only one strand of DNA) and topoisomerase II (it is able to cut both strands of DNA).