Answer: Two molecules of H2A
Explanation:
Structural organization of nucleosomes were determined by isolating them from unfolded chromatin and it has been found that the basic units of chromatin are the nucleosomes which consist of histone octamers of two molecule each of histone H2A and other histone molecules like H2B, H3 and H4. The histones are wrapped around with 147bp of DNA in almost two (2) turns.