On any given blank there are a number of genes but not all the genes will be coding for patients

The right answer is B. Chromosome

In its most scientifically rigorous definition, a chromosome is a fully condensed structure of chromatin.

In optical microscopy, condensed regions formed of heterochromatin and decondensed regions of euchromatin are distinguished on the chromosomes. The genes expressed are located mainly at the level of euchromatin.