The alternative valence states of $DNA$ bases in $A=T$ and $G=C$ pairs are known as:

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.

Match the following columns:

Column-$I$	Column-$II$	Column-$III$
$(1) \ 1952$	$(a)$ Watson and Crick	$(i)$ Double helix model of $DNA$
$(2) \ 1928$	$(b)$ Friedrich Miescher	$(ii)$ Proof that $DNA$ is genetic material
$(3) \ 1869$	$(c)$ Griffith	$(iii)$ Nuclein
$(4) \ 1953$	$(d)$ Hershey and Chase	$(iv)$ Transforming principle

Which of the following statements is incorrect?

What are informosomes?

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