Consider the following statements and select the option that correctly fills the blank:(I) The interphase nucleus has a loose and indistinct network of nucleoprotein fibres called _A_ (II) Primary constrictions of chromosomes are also called _B_.(III) A part of chromosome beyond non- staining secondary constriction  is called _C_ (IV) Kinetochores are _D_ structure.

The interphase nucleus has a loose and indistinct network of nucleoprotein fibres called chromatin.Every chromosome essentially has a primary constriction or the centromere on the sides of which disc shaped structures called kinetochores are present. Few chromosomes have non-staining secondary constrictions at a constant location. This gives the appearance of a small fragment called the satellite.