The number of base pairs (bp) in a typical nucleosome of DNA helix is:

The correct answer is Option (2) → 200 bp

Option (2) 200 bp — Correct. A typical nucleosome contains about 200 bp of DNA helix wrapped around the histone octamer. The nucleosomes are the repeating units of chromatin, seen as ‘beads-on-string’.

NCERT Extract:
Packaging of DNA Helix – “… The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome (Figure 5.4 a). A typical nucleosome contains 200 bp of DNA helix. Nucleosomes constitute the repeating unit of a structure in nucleus called chromatin, threadlike stained (coloured) bodies seen in nucleus.”