Final answer:
The common histone that is not part of the nucleosome core particle is H1. Hence the correct answer is option A
Step-by-step explanation:
The common histone that is not part of the nucleosome core particle is H1. The nucleosome core particle is made up of two copies each of histones H2A, H2B, H3, and H4, forming an octamer. Histone H1 is referred to as the linker histone, as it binds to the linker DNA between nucleosomes and helps to further compact the chromatin fiber.
Hence the correct answer is option A