Thymine is present in which of the following?

Read the following statements and choose the set of correct statements:
$(a)$ Euchromatin stains light.
$(b)$ Heterochromatin is transcriptionally inactive.
$(c)$ Histone octamer contains eight molecules of histone proteins.
$(d)$ Packaging of chromatin at higher level requires additional set of proteins that are referred to as non-histone chromosomal $(NHC)$ proteins.
$(e)$ In a human diploid cell,$6.6 \times 10^9$ base pairs are present,not $6.6 \times 10$ nucleosomes.
Choose the correct answer from the options given below:

How is the $DNA$ molecule useful to higher organisms?

Which of the following is genetically inert and does not transcribe messenger $RNA$ for protein synthesis?

Assertion $(S)$: $RNA$ does not contain $T$ (Thymine).
Reason $(R)$: $DNA$ does not contain $U$ (Uracil).

The double helix model of $DNA$ was proposed by