$DNA$ replication is semi-conservative as

Complementary $DNA$ $(cDNA)$ is complementary to

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:

$E. coli$ has only $4.6 \times 10^{6}$ base pairs and completes the process of replication within $18$ minutes; then the average rate of polymerisation is approximately

Match the following columns:

Column-$I$ (Enzyme)	Column-$II$ (Function)
$P$. $DNA$ Polymerase	$I$. Synthesizes $DNA$ strand
$Q$. $DNA$ Helicase	$II$. Breaks $H$-bonds of $DNA$ strands
$R$. $DNA$ Ligase	$III$. Joins $DNA$ fragments

Which plant was used by Taylor to prove semiconservative replication at the chromosomal level?