The variation in $DNA$ among different organisms is due to the sequence of:

How many polynucleotide chains are present in the structure of $DNA$?

Adjacent nucleotides in a polynucleotide chain are joined by

Which one of the following statements about Histones is wrong?

Read the following statements and choose the set of correct statements:
$(a)$ Euchromatin is loosely packed chromatin
$(b)$ Heterochromatin is transcriptionally active
$(c)$ Histone octamer is wrapped by negatively charged $DNA$ in nucleosome
$(d)$ Histones are rich in lysine and arginine
$(e)$ $A$ typical nucleosome contains $400 \ bp$ of $DNA$ helix
Choose the correct answer from the options given below:

Which organism has a $DNA$ consisting of $4.6 \times 10^6 \, bp$?