In which type of $DNA$ replication,out of the two newly formed molecules,one is purely new and the other is entirely old?

$E. coli$ has $4.6 \times 10^6 \text{ bp}$, its rate of multiplication during replication is about $ . . . . . . $ per second. (in $\text{ bp}$)

Given below are two statements,one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ $\text{DNA}$ replication occurs within a small opening of the $\text{DNA}$ helix,referred to as the replication fork.
Reason $(R):$ During transcription,the discontinuously synthesized fragments of $\text{DNA}$ are joined by the enzyme $\text{DNA}$ ligase.
In the light of the above statements,choose the most appropriate answer from the options given below:

The Okazaki fragments in $DNA$ chain:

Choose the correct option for $Reverse \text{ } Transcriptase$.

At what time intervals did Meselson and Stahl take samples after transferring the bacteria to a $^{14}NH_{4}Cl$ medium?