The flow diagram illustrates several stages involved in the replication of a lagging strand of DNA. At which stage of DNA replication is the enzyme DNA ligase used?
- AThe DNA double helix begins to unwind.
- BThe single strands of DNA are exposed.
- CNew complementary DNA fragments are synthesised in the $5' \text{ to } 3'$ direction.
- DThe fragments of newly formed DNA are linked together.