In Meselson and Stahl's experiments, heavy $DNA$ was distinguished from normal $DNA$ by centrifugation in

Given below are two statements :

Statement $I:$

DNA polymerases catalyse polymerisation only in one direction, that is $5^{\prime} \rightarrow 3^{\prime}$

Statement $II:$

During replication of $DNA$, on one strand the replication is continuous while on other strand it is discontinuous.

In the light of the above statements, choose the correct answer from the options given below :

Semiconservative model of $DNA$ replication was proposed by which workers in eukaryotes

Semi­conservative replication of $DNA$ was first demonstrated in

Which one of the following correctly represents the manner of replication of $DNA$ ?