The normal pattern of replication would be affecting the mutation in one of the replication forks. This makes sure that option (a) is incorrect.
Replication would be completed at both the ends. The new progenies would be formed in case of a circular or linear DNA molecule. But the only factor is that the time taken would be longer. This makes option (b) as the incorrect choice.
Replication would be continued both in the leading, as well as in the lagging strand, which shows that option (c) is incorrect.
The replication fork travels twice the length, as opposed to its normal travel time. This shows that almost twice the quantum of time is required, for the synthesis of DNA to be completed. This proves that option (d) is the right option.
Hence, the right option is (d) Replication would take twice as long.