Which complementary base pairing is present in the structure of $DNA$?

Which one of the following statements about Histones is wrong?

In $B-DNA$,one full turn of the helical strand contains

Assertion $(S)$: $DNA$ structure contains $A-T$ complementary base pairing.
Reason $(R)$: $DNA$ structure does not contain uracil.

Assertion: In a $DNA$ molecule,$A-T$ rich parts melt before $G-C$ rich parts.
Reason: In between $A$ and $T$ there are three $H-$ bonds,whereas in between $G$ and $C$ there are two $H-$ bonds.

The core particle of a nucleosome is composed of how many histone proteins?