Which of the following uses $RNA$ as a template for $DNA$ synthesis?

$A$ $N^{15}-N^{15}$ $\text{DNA}$ molecule is continuously replicated in $N^{14}$ medium,then what is the percentage of heavy $\text{DNA}$ in the $4^{\text{th}}$ generation (in $\%$)?

$DNA$ gyrase,the enzyme that participates in the process of $DNA$ replication,is a type of:

$E. coli$ cells were allowed to replicate in a medium containing radioactive thymidine for $5$ minutes and then transferred to a normal medium for further replication. Which of the following observations will be correct?

$DNA$ gyrase,the enzyme that participates in the process of $DNA$ replication,is a type of

Which of the following diagrams correctly represents the process of $DNA$ replication at the replication fork?