Which of the following contains the essential enzymes for protein synthesis?

Mark the correct match.

Explain the following terms:
$1.$ Leading strand - Lagging strand
$2.$ $t-RNA$ - $m-RNA$
$3.$ Monocistronic - Polycistronic

Study the given figure of a nucleosome and select the option that correctly identifies the parts $A, B$ and $C$.

How many of the given statements $(i-iv)$ is/are correct?
$i.$ In transcription,adenosine pairs with uracil.
$ii.$ Regulation of lac operon by repressor is referred to as positive regulation.
$iii.$ The human genome has approximately $50,000$ genes.
$iv.$ Haemophilia is a sex-linked recessive disease.

Select the $CORRECT$ statement from the following.