The correct option is A Heitz
Term heterochromatin and euchromatin were first coined by Heitz. Chromatin is made of nucleoprotein. Chromatin is a complex of macromolecules found in cells, consisting of DNA, protein and RNA. Chromatin is found in two varieties: euchromatin and heterochromatin. The heterochromatin is condensed in the secondary constriction I and II of the chromosome. Heterochromatin is a tightly packed form of DNA, which comes in different varieties. These varieties lie on a continuum between the two extremes of constitutive and facultative heterochromatin. Both play a role in the expression of genes.