In which direction does the lagging strand elongate relative to the replication fork?

The lagging strand during DNA replication elongates away from the replication fork. This occurs because DNA polymerase, the enzyme responsible for synthesizing new DNA strands, can only add nucleotides to the 3' end of a growing DNA strand. As the replication fork opens up, the leading strand can be synthesized continuously in the direction of the fork.

In contrast, the lagging strand is synthesized in short segments called Okazaki fragments, which are produced in the opposite direction of the replication fork's movement. This necessitates the periodic synthesis of these short fragments, followed by their joining together as more of the template strand becomes available. Therefore, while the replication fork progresses, the lagging strand is effectively being built away from the fork, leading to the characteristic discontinuous synthesis associated with it.

Thus, the correct answer accurately reflects the specific orientation of lagging strand synthesis in relation to the advancing replication fork.