The enzyme used to join the DNA strand that is replicated in small segments is called DNA ligase.

Here's why:

* DNA replication in eukaryotes is discontinuous on the lagging strand. This means that it is synthesized in small fragments called Okazaki fragments.

* DNA polymerase can only add nucleotides to the 3' end of a pre-existing strand. This means it can't create a new strand from scratch.

* DNA ligase comes in to fill the gaps between the Okazaki fragments, creating a continuous strand of DNA.

So, while DNA polymerase is responsible for the actual synthesis of the DNA strand, DNA ligase is crucial for joining the fragments together to form a complete, continuous strand.