Final answer:
The lagging strand is synthesized in short segments called Okazaki fragments because DNA polymerase can only synthesize in the 5' to 3' direction and the lagging strand is oriented 3' to 5' at the replication fork.
Step-by-step explanation:
The lagging strand cannot be replicated as a continuous segment by DNA polymerase because DNA polymerase can only synthesize DNA in the 5' to 3' direction, and the lagging strand is oriented in the 3' to 5' direction relative to the replication fork.
As a result, the lagging strand must be synthesized in short segments called Okazaki fragments, each requiring a primer to initiate synthesis.
These fragments are then linked together to form a continuous strand.