What is the nature of histone proteins?

The correct answer is Option (2) → Basic

A protein gets its charge from the amino acid residues with charged side chains. Histones are rich in lysine and arginine, which are basic amino acids carrying positive charges in their side chains. So histones are positively charged, basic proteins. This is why they can hold the negatively charged DNA that wraps around the histone octamer in a nucleosome.

Option (1) Acidic — Incorrect. An acidic protein would be rich in acidic amino acid residues. Histones are rich in lysine and arginine, which are basic.

Option (2) Basic — Correct. Histones are basic proteins because of their many lysine and arginine residues.

Option (3) Neutral — Incorrect. Histones carry a clear positive charge, so they are not neutral proteins.

NCERT Extract:
Packaging of DNA Helix – “… In eukaryotes, this organisation is much more complex. There is a set of positively charged, basic proteins called histones. A protein acquires charge depending upon the abundance of amino acids residues with charged side chains. Histones are rich in the basic amino acid residues lysine and arginine. Both the amino acid residues carry positive charges in their side chains.”