Study the given figure of nucleosome and select the option that correctly identifies the part $A, B$ and $C$ ?

$A\;\;;\;\;B\;\;;\;\;C$

A given double stranded $DNA$ molecule is $1,00,000$ base pairs long. The length of this $DNA$ molecule will be

$DNA$ was first discovered by

Cytidine is a

The double helix model of Watson and Crick is known as