Which of the following statements about nuclear genome organization is CORRECT?
选项：

A:Nucleolar organizer regions are portions of chromosomes where ribosomal RNA genes are clustered and transcribed.;
B:Centromeres are sequences located at the ends of each chromosome.;
C:Telomeres are where sister chromatids adhere to each other and where spindle fibers attach during cell division.;
D:Chromosome organization is random in the interphase nucleus.